because, considering the whole implementation of INF, it makes no sens. Plus, if someone shoots a weapon out of my hand in real life, it won't just mysteriously drop on the floor. Each time it happens with IBT, it's not the fact that the weapon was dropped that gets someone killed... it's the confusion caused by having your weapon suddenly dissapear.
Also, i'd like to mention the modified jumping hight. This is a major problem with IBT (or what ever mutator running on this server that causes it). This feature should be removed until corrected. Do I really need to explain why?