How will it work when the PHB comes out if some players want to use feats, and some don't? Will adventures assume them?
I don't think it's actually possible for an adventure to "assume" feats. There will be plenty of feats anyway, so how the hell the adventure designers are going to design their adventures
differently by assuming feats are used?
Please, no. Let's not errata every questionable line of text this edition. Let's keep errata to a minimum and only use it when it's actually important. The endless errata train is a highly negative thing, and for something where the dm can simply rule how it works in his game, I really think errata is... excessive.
To repeat: Please, no errata except to fix things that badly need fixing.
This is a good point, but I wouldn't even call those "errata". Errata-corrige are corrections to the text, not clarifications, so those would rather be FAQs or "Sage advice".
I would be intrigued anyway if WotC decided
not to provide official rulings for ambiguous situations. I understand the potential problem with organized play (which is a big part of 5e), but still I wouldn't dislike if they forced each DM/group to make their own ruling on certain things, especially corner cases and rarely coming-up combinations.
The problem some see isn't with hit dice -- it's with other things that recover after a short rest and can be immediately used for benefit and then there should be nothing preventing characters from taking another short rest. The poster child is the Fighter healing ability Second Wind.
So Fighters can recover all hit points without resorting to using hit dice using (multiple) short rests.
More generally, I think the problem is with
healing and other unbounded replenishment abilities (there might be none at the moment).
For example, take a look at Arcane Recovery: it is not unbounded because it specifically says "once per day" even if it based on a short-rest. So no problem here. But if it didn't say so, a Wizard could just take additional short rests until regaining all her spells slots, and I'm sure there will be arguments about this!
However, while
in theory unlimited self-healing sounds like a problem,
in practice it depends on how the DM runs the adventures. I still don't have a clear opinion on this, but while a badly wounded Fighter might force the party to stop for N hours to regain Nd10 hp, he might also just call it a day and take a long rest, hence regaining
all hp.
At the same time, as @mips says, I don't think this is the intent of Second Wind. I don't think it's meant to represent
regenerating wounds but rather
ignoring some damage you just took
during the current combat. That's why it says "on your turn". IIRC in the playtest it required you to take an action i.e. forgo your attacks for a round, while in Basic it's more conveniently a bonus action. Still, it feels to me this is supposed to work only
during combat, not afterwards (the short rest is to
reset the ability, not to
use it).
Maybe I'm wrong, but if this is the intent, then the current design is not good. I would like to HR this so that it only heals damage taken during the current (or just ended) encounter.