Eh, for the most part it's safe to pack some kind of shield or heal for one's self or in-case the heals go down. Especially if you like to wander off to random corners of the map. It's not really technically necessary, but for the most part when doing random stuff with random players the healers aren't just spamming heals 24/7 and can easily accidentally be in the middle of something as your health gets chunked.

(and of course the ever-present possibility of someone involved in the dungeon not being super good at what they're doing... or at least, for the moment. Stuff happens )

Never seen those trucks with the signs saying "if you cant see my mirrors, i cant see you"? Same theory applies here.
-Stay infront of the healer
-Use their healing springs and all those other cool resto skills, they keep you alive
-Red = dead
BUT
-Learning to keep yourself alive is a great skill also (eg. vma)
Food for thought

It's true that self healing is often all you need once you know to avoid/game the mechanics well enough. The game struggles at times to know whether it's Elder Scrolls where each person is a self-sufficient character in their own right or whether it's an MMO where the holy trinity is well... holy.

For me it just means that healers need to adapt to the current situation, its less and less acceptable to simply heal and provide group buffs. You're better off under healing, allowing those self heals to fill the gap and then filling the rest of your time with DPS.

@firedrgn: Are we talking about "death due to sudden damage burst" or "health slowly going down until death and no healer caring about it"?

The former can happen anytime, even with good healers. You need to take their reaction time and the game's mechanics into account. Depending on what you and they are doing at the respective moment, when your health goes down rapidly, they have to 1) see it and react, 2) potentially swap bar to their "oh-sh.." button (BoL, healing ward, etc.), 3) potentially wait for the global skill cooldown (1.1 seconds) to expire, and 4) press the button.

If your health goes from full to zero in say less than 1.5-2 seconds, the aforementioned combination can cause the healer to not be able to react quickly enough. In such cases, it's indeed the DD's own responsibility to emergency self-heal, use a shield etc. Which means DDs should be aware of the situation and know in advance when there's potential for damage bursts. For the most part, stay out of red, don't stand in front of the boss, things like that.

For the health slowly going down, well yeah that's something that shouldn't happen. Of course, healers do much more than just spam springs or BoL. The less healing they have to do, the more time they can spend with support (combat prayer - which happens to heal too, ritual, shards, orbs, lightning wall, ele drain, power of the light, heavy attack for aether, things like that).

So if the DDs have a little self-heal or shields to keep the slowly creeping damage at bay, it makes things much easier for the healer and smoother for the group.

1) You can't outheal oneshots, and there's usually at least 1 oneshot mechanic in every dungeon's last boss, sometimes even before that. These mechanics are meant to make players be active, even if the dedicated tank has aggro. It can be a projectile you have to dodge/block, it could be a GTAoE, it could be a disabling mechanic.

2) For a healer to effectively heal, the group needs to be relatively close. One would think the safest place to be is farthest away from the boss, and one would be wrong (and also dead) as many bossess have dash mechanics to nab the smartest people in the world staying all the way to the other side of the arena. Also, that's where there are no heals. A dedicated healer (a good one, at least) concentrates their healing in a relatively large circle (healing spring's radius) near the boss, that's where most of the red is, but it's also where most of the healing is. Spamming BoL is not an option as it will deplete the healer's magicka reserves in seconds.

So, if you can't be bothered considering oneshots mechanic and you like to be as far away as possible from the danger, yes, you definitely need self heal, shield, and every protection you can stack, healers can't help you.

Otherwise, no, healers heals just fine. If you consider trials, people don't use self heals, unless asked, they trust their healers.

As a healer, if I have a DD that needs a passport to fight a boss, after I asked 3 or 4 times to stay closer, I generally just let them die. It's not my fault if they just can't understand I can't target people to heal them.

On the bright side, you don't really need a healer for dungeons. Right now, the only place where you really need a healer is veteran trials. In dungeons, you bring a healer for the SPC bonus of for easy resources. Every class has a fairly reliable self heal that can keep yourself (and sometimes a friend) up while dealing all the damage you can push out, so, it's not unusual to see group of 4DDs or 3DDs+1tank.

Hope this helps.

I my opinion you should always have a selfheal or shield. Usually you shouldn't have to use it but healers can make mistakes, you can run out of sight or other things. Of course it can also happen that you don't have a healer when using the dungeonfinder.