Recently came back to ESO (again) and have leveled up my NB almost exclusively via Battlegrounds and thought I'd share my feedback about where the quality of ESO combat can improve to feel more fluid. These changes might affect balance in subtle ways but are not directly related to balance but rather the modernization of the general feeling of combat to help the game compete with other games by further enabling the action-combat feel of this game. Not that it matters hugely to my arguments, but in-case it helps I am a relatively competent MMO-PvPer, have achieved Gladiator in WoW for what it's worth and been in a top 4 Guild Wars GvG guild when I was playing on EU in the past.
Oh my god. This issue is way bigger than you'd think at first. I don't know if the ZOS developers are just sadistic but there is so much stupid crap to get tripped up on in your BGs and it really clunks up the game for anybody that likes to use their sprint key. I totally understand wanting to include LoS, wanting to have non-uniform terrain so that the BGs don't just look like flat wastelands, and even the use of Z-axis (including those floorboards that you can fall through if you're not careful on the third floor of the mage school map)... but the amount of freaking little pebbles and tiny lips on the ground across the various battlegrounds that you should simply be able to path over without spamming jump... those in my opinion really need to be smoothed out. It's far too easy to waste a dodge roll and go nowhere because of some insignificant little crack in the ground.
This is a compound issue, affected heavily by my previous point. The fact that you LOSE all of your sprint momentum magically upon sprint jumping feels awful. Where are we getting these air brakes from?? If you're jumping at normal run speed your momentum should line up with that... if you're jumping while sprinting, you should obviously have more momentum. The terrain already creates a need for jumping over every little mismatched jagged rock sticking out of the ground, don't further punish your players with a clunky feeling sprint-jump you evil sadists.
Mid-air weapon swapping
Yuck, not being able to use your free-time while falling off of any given Z-axis to swap to a more preferable weapon feels incredibly gross and needlessly limiting. Let me prepare for the fight ahead ffs. You should be seeking to build your combat in such a way that it can (as long as it doesn't break the general theme and fantasy of whatever you're trying to develop) reward players who are more resourceful and more able to min/max their second to second gameplay, whenever possible. This by extension increases the arc of possible mastery of the game, thereby elongating the natural skill-cap progression of anyone who wants to improve at the game. This also technically is a form of protection against over-homogenization I would argue, because everyone's natural tendencies are at least a little bit different (in terms of execution, prior to mastery of game knowledge, and even sometimes after that), so opening that up as much as possible will only be a benefit to preventing the game from getting stale over time in my humble opinion.
Control over spell queuing
This might only be a noticeable issue because my latency here in the mid-west U.S. is floating around the 110-150 range most of the time. I don't know where your mega-servers are located or how the routing is done, but when spamming keys in order to make sure they register just as my GCD is coming up (which by the way players shouldn't have to download a mod to track...), often times I'll accidentally queue up an additional spell in-between weaves which will interfere with my intentions. You could argue this is an incentive to be more mindful and careful about your exact timing and all of that, but I think this is outweighed by the natural tendency of action and MMO gamers to want to mash their fancy mechanical keyboards cause reasons. When lag enters the picture it can be really hard to know if a key is going to register correctly when working with animation locking and GCDs, so players tend to like to mash a bit as an insurance policy. If it's at all possible for you to give players control over disabling or setting custom spell-queuing latency in the interface in the same way that WoW does, that might be a good idea.
I'm sure there are more but these are what I've come up with most recently. Like to hear what more experienced ESO players think about all this