No, why not. Being disguised requires a certain amount of skill and it's not soo easy to deal with a good disguised enemy. On the other hand, the majority of players svcks at being incognito and will fail.
I still like the idea that you can take one of the basic abilities of the class you take.
Medic: Steal a revive needle
Engineer: Weapon boost
Soldier: Ammo gain (how much it would gain from having a friendly toss it 2 you)
If it was real life and you were stealing from the corpse you would take the most valuable thing. The abilities listed are the basic abilities of each class and that is why it makes sense. Of course this is a video game and not real life but I making a point. You kill the engineer and whatever he uses to buff guns would be there. Pick it up buff your gun and be on your merry way.