1.) The reason enemies are there is to be an obstacle in the way of getting what you need. Giving them drops ruins this. If you give them drops then players are tempted to kill them all. We never intended for all enemies to be killed.
That's a good point, but an obstacle isn't fun by itself. Overcoming an obstacle can be fun, but if conquering the obstacle (whether by violence, stealth, diplomacy, or anything else) doesn't reward me in some way, I have no incentive to conquer it at all. As it is, my most effective method of getting to the next "reward" is to see how fast I can run past every enemy on my way to the next mission, which invariably means several screens of running and hopping. Unfortunately, I'm discovering that playing that way is extremely boring. I can engage the enemies to relieve the tedium, but since there's no metagame reason for doing that it seems pointless.
Right now, I think the combat's the strongest element of the game in terms of immediate, short-term fun. If you don't intend for the enemies to be fought all the time, which is an awesome idea, I think you should give us an alternative that's equally satisfying. Otherwise, just have them drop 0.1% of an enchant charge or something, just so I don't feel like I'm wasting my time.