I'm quite confused as well in regards to this aversion to stamina regeneration and it most definitely feels like its due to one of two reasons:
1) Not understanding the concept behind stamina/health, (which has been extensively explained in this thread and in various others) and assuming its exists to be "easy mode"
2) Not being "realistic" or "immerse"...
In regards to the first point, like I said the mechanics have already been covered so no need to keep beating that dead horse. My opinion however is similar to a couple of other people and also has to do with the fact that games are suppose to be fun to play, not obnoxiously frustrating or tedious. Non regenerating stamina and extremely limited resting (as the only means to regen that stamina, and yes that includes healing by priests as that is limited as well and would only be available again by resting) is honestly a very cheap way of making a game more challenging, and in fact only makes it take longer to do things (you either reach a point where you can no longer fight and cant rest anymore, and are forced to reload an earlier save, or you constantly back track in order to regen, or the worst of all which someone mentioned above... forced to carry a ton of healers in the party) and can eventually force you to always play or use the same "best" tactic which makes combat repetitive, dull and doesn't leave room for creativity.
In regards to the second point... where is this notion of "this RPG, which is set in a fantasy world with soul magic, dragons, god like races, fish people etc has to be super realistic" coming from? Sorry but it does not, and I would imagine most people who backed it don't expect it to be a realist medieval combat simulator. Sawyer has repeatedly mentioned how the crux of challenge in combat is tactical not strategic. That doesn't mean you should never think of long term consequences, that's the point of health, but it means the challenge has much more to do with each encounter than with having to worry about how every single one of your combat choices is going to direly impact your next 5 encounters. Also, being forced to carry a bunch of healers, or having to stop after only a few fights and go back to rest somewhere, or always using the same strategy to never take damage and only ever rest because your party is tired after staying up to long or running too much (thats what fatigue was for in BG) is the complete opposite of immersion.
There are some great ideas in regards to low stamina affecting cooldowns, ability efficacy etc and in the system we know of right now, all that would have an affect during combat, but I fail to see why punishing the player to that extent after combat is fun or immersive. This is not a competitive multiplayer game, its not about you being more skillful than other people at combat, it's not about bragging rights because you want or can play on a harder difficulty than other people.