Obvious glitches aside, I think that returning to the precedent of Werecreature game-play would make the experience much better. Forced transformations and the need to kill should be part of playing as a Werecreature character, consequences and all. This would include bonuses to Hand to Hand, Unarmored, resistance to normal weapons, Night eye and detect humanoid etc all in the same package and if you transform in the middle of an important quest or lose health because you don't kill then it is your own fault and you should deal with the consequences.
I pretty much agree with you, and mods that can make this happen will be among my favorite. As long as it doesn't purposely let the game break so badly that you can't continue playing, then it's all good. However, what I don't necessarily agree with...
There are many things that Bethesda should take more time developing and implementing, this is one of them.
I'd be all over the idea of extending development time to make werewolves better, but that's simply not how commercial game development works. There are a million things the developers would want to continue working on to make better, and if they were allowed to, the game would never be finished and released. That's why it's important to set a release date when you have a good idea of when things will be finished, and stick to it as best as you can even if it means dropping or toning down planned features when you see you can't do them as well as you want as the release date approaches.
I personally would want them to take extra development time for werewolves because I like them and think they make an awesome and worthwhile addition to the game, but there's many other things other people would want them to take extra development time for instead, and its simply not feasible to do it. As much as I want it, I understand it's not always possible for them to do (it's also why I go for the PC version, so modders can continue to flesh out what Bethesda couldn't finish).
I don't understand why it needs to be fun to play. It's a curse. How are curses fun? Especially when you're on the receiving end.
You play games to have fun. If it's not fun, why are you playing? You can have curses and let bad things can happen while still being fun, however, and that's the important part to keep in mind.
Failing a quest or being prevented from doing a quest because of it is fine, as long as there's still other stuff to do. Being forced to change is fine, as is having to kill an (innocent) NPC to stay healthy, as long as it doesn't put you in a situation where you couldn't avoid being in the middle of a quest when a forced transformation hits and you're forced to kill an important NPC (which would then break the quest line you've been working so hard at). Having something break because you didn't keep track of the day/time is fine (it was your fault), but having it break despite taking all the precautions you could is bad (it was not your fault). A less-than-desireable outcome is one thing, but completely breaking an important quest chain because of something you couldn't avoid is entirely another.
Bethesda introduced a few systems which would work really well for helping with this (regional crime, witnesses, radiant story which can switch quest givers/receivers in case they die, etc), and some things can be added to help even more. I'm very interested to see what mods will be able to do.