Personally I'm against the idea of enemies having useful drops.
Most common sense or logical applications of "enemies" run on the idea that they are obstacles that try to prevent you from completing your objectives. Most common sense uses for enemies are as challenge to overcome to get to the reward they are trying to prevent you from reaching.
When you provide a direct "reward" for killing enemies, you've turned them into challenges with rewards already built in. This sounds good by itself, but it makes some assumptions as to how the player should play the game. It makes fighting them better, but that's the only thing it makes better.
The downside to this is that it reduces the effectiveness of the enemies as an obstacle or deterrent. It also runs on the assumption that destroying enemies is the only way towards your goal, and ignores other possibilities.
Yes, it is true that not having a reward for killing enemies turns them into purely obstacles that keep you from getting to where you want, but if you think about what enemies are supposed to be in the game's universe, this makes sense. They're "enemies", that's what they do!
They're "bad guys", and to me it makes sense that running into "bad guys" should be, well, "bad" for you!
In some games, rewarding players directly for killing enemies makes sense because those games are purely about combat. If combat is the only thing you do and is in fact your primary objective when playing the game then yes, in those cases I believe it would make sense. However, in the case of A Valley Without Wind, doing this would be bad for a lot of the other possibilities available in the game.
Again, this is just my opinion, obviously other people believe otherwise. It wouldn't kill the game for me if enemies started dropping useful things, but it certainly wouldn't be a positive to me.
I say if they're too easy to avoid, then that's what needs addressing.
Not across the board, mind you, but if it's easy to avoid everything then there's something a little awry there!
I believe this as well to some extent.
If you're dodging most of the enemies on your way to where you want to go, then I think that's a perfectly legitimate way to play the game. In fact, you might want to even get some cloaking enchants and optimize your character for that style of play if that's how you prefer to do it.
I tend to kill a lot of the enemies that get in my way, but I still dodge maybe half of them and that still feels right to me.
If it gets to the point where too many people are all dodging the enemies rather than killing them at all, then I think it's the difficulty or effectiveness of said enemies which would need changing rather than trying to reward people for killing them.