I agree with your points, but I'm pretty sure the reason for the feeding animation is that the animation system in the game isn't designed to pair two actors together for a combined animation. Lining up two actors for such a delicate animation as feeding is just not possible without reworking something that'd require a lot more than simply making a new animation. The game can make two actors perform animations at the same time, but that's hugely different than lining two actors together for a combined animation, both in complexity and framework requirement.

Don't get me wrong, I was hugely disappointed in the feeding animation when I saw it during the beta. I'm a huge fan of playing a vampire character and seeing the animation makes me want to facepalm every time. Perhaps this is why I rarely ever feed.

I'm not hugely knowledgeable in different kinds of vampire lore, but I'm fairly sure that a vampire shouldn't be able to feed on him/herself. The same way as eating your own body parts in the face of starvation actually works against you (trauma from losing a part of your body requires more energy to recover from than the amount of nutrients you get from it). Though feeding on another vampire could be possible depending on the physiology of the vampire in TES lore.

As for gaining buffs for a duration sounds really interesting. I'd love for a continuation on the vampire questline, which could be used to unlock new kinds of abilities and what not. Perhaps in a future DLC to expand on the Werewolf and Vampire story you could - upon completing the questline - unlock a Vampire Lord transformation Ultimate for the Vampire and a regular Ultimate on the Werewolf version to even out the Ultimates on both sides.

I do hate how the vampires look in later stages in the game as it is. I think it would really improve the gameplay experience of vampires if they'd add an option to "magically" hide your true form through illusion magic, which in TES Lore is a thing vampires are naturally good at anyway. Or ZOS could just make later stages look less like crap (sorry artists, I know you meant well!)

Another option they could add is the possibility to buy (and/or craft) Potions of Blood, a vampire exclusive kind of potion that would lower your vampirism stage by one and give you buffs X and Y. This could allow the devs to tie the fire vulnerability to the stages of vampirism: +10% at the first stage, +40% at the fourth stage? This could allow players to almost fully negate the fire vulnerability when needed. Let's say you're a Nord Vampire Nightblade Tank and you want to go do City of Ash on veteran difficulty. Sure, you can manage it (did it with 2.7k Max HP), but it's insanely hard and even the slightest mistake or lagspike will result in almost instant death.

I'm not saying that we should have all the benefits of vampirism and none of the downsides. Reduce the effectiveness of the buffs with the stages as well? Though with every patch the benefits of being a vampire seem to go down. With 1.6 Nightblades are getting a Leeching Swarm equivalent Ultimate that costs less (Soul Tether) for example. Also many of the the previous vampire nerfs (that should have been nerfs to Death Knights Dragon Knights instead) have made being a vampire more about the downsides and less about the benefits.

Once I started the quest to become a creature of the night on the third day of early-access, I was incredibly excited about the place that the quest took place. The crypt looked great and very feral vampire-like. Now with the introduction to Outlaw Refuges with 1.6 and the justice system, ZOS could take a look at creating Vampire and Werewolf exclusive zones - perhaps unlocked through a quest - where vampire players could hang out and those interested in RP could do their thing. Though, less blood and bones, more sophisticated vampire stuff please. We're not all feral beasts!

I'd be okay with a vampire section added to each of the Outlaw Refuges, or these could have an access tunnel to the safe-houses and hideouts mentioned above. This would be the place to either craft or buy the above mentioned Potions of Blood, buy other vampire specific items and so forth (Vampire Motif? Loved the vampire armors in Skyrim). I really think these places would be a great success with the players. Kind of a "Dawnguard DLC" style addition to the game would be greatly appreciated and a huge success. Both with the fans and monetarily to the company *winkwink*.

Ultimate:
Devouring Swarm was one of the best Ultimates out there because of the AoE damage combined with the life leech. In 1.6 Soul Tether is in many ways far superior of a Ultimate. It deals huge AoE damage on activation and constant damage combined with life leech for 4.5 seconds (Bats is 5 seconds). True, the range on Bats is larger, but in many cases this doesn't matter. In PvE, monsters are usually packed tightly anyway and in PvP the increase in burst damage through using Soul Tether is far superior to the increased range.

Drain Essence:
I loved using this ability all through leveling up and in early PvP (1.0). It's hugely powerful when used right, especially the Invigorating Drain morph. Though this ability has seen it's fair share of nerfs along the way as well. At first, you could use it on the same target only after a certain amount of time, which made it a lot less powerful (but still useful) when fighting longer fights; champion monsters or players with survivability based characters. With the change that disabled the usage on the same target, completely destroyed the viability of this ability. The only thing where it could be a viable option over any other ability is grinding single normal monsters. Which means that the ability is nearly completely useless in any given end-game PvE situation.

Now, with the most recent change that allows players to break free from the effect will even further limit the usage of this ability. There is no justification in using this ability in PvP anymore, apart from flavor perspective. In essence, you have an ability that will most of the time grant you one third of the effect because of human reaction time combined with lag, it'll in most cases manage to tick once, without the ability to use it twice in a fight. This basically means that the ability we will have in 1.6 PvP is:

Channeled ability (can't block cast)
Cost: 1848 Magicka
Range: 7 meters (close to melee range)
Deal 1260 Magic Damage, restore 159% as Health and Stamina.
Gain 5 Ultimate.
Can be used once against any given target.

To compare, Nightblades have access to this neat spell:
Instant Ability (can block cast)
Cost: 1158 Magicka (lower cost)
Range: 28 meters (has bow equivalent range)
Duration 10 sec (fire and forget)
Deal 2336 damage, heal for 26% of the damage every 2 seconds.
While slotted, you gain 8% more healing received. (You gain constant healing and improves all of your other healing abilities)
Also restores Ultimate through class passives


Mist Form:
This one is still great in matter of flavor and usefulness and it's getting returned to it's former glory with 1.6 (+40% movement speed.) Great utility skill. Great work ZOS!

Passives:
- Feeding stuns target for 4 sec - Ehh... You mean the feeding skill that's unusable in any serious end-game scenario? Am I missing something here?
- +10% Stamina and Magica Recovery - Excellent passive.
- Infect another player with vampirism every 7 days. Very nice. Not in any way helpful to your performance, but flavorwise awesome.
- Reduce damage taken when below 50% HP up to 33%. Very powerful for tanks. Not so much on other play styles. I'd love to know the actual inner workings of this passive though. At what percentage do I get the 33% benefit? What's my reduction at 25% HP? What about 40%?
- Lessened health regeneration downside from stages 2 through 4. I'd love to know the exact numbers, but sounds good.
- Increased movement speed in sneak and hide faster at night. Brilliant flavor and great fun to use. Not exactly a bonus in PvE, but can be useful in PvP. Estimating the value of sneaked movement speed is hard, but I'd say it's up there. Though you can get the exact same effect through a crafted set-bonus.

TL;DR - Vampire active abilities apart from Mist Form are pretty much useless as they are weaker versions of my class abilities or straight out bad (looking at you Essence Drain). The passives are pretty sweet, but I'm not sure if they alone with Mist Form (still takes up your skill slot, so it should compete with every other skill in the game) could warrant hugely reduced health recovery and a +40% Fire Damage taken, given the fact that two of the game's classes specialize in Fire Damage dealing and the third is very good at it too, through mainly using a destruction staff (DK and Templar, later referenced to Sorc).