I think a cool thing would be to add collisions to Minecraft. The idea is that you cannot pass directly through the player/mob, so that the entity you are trying to pass through blocks you. What do you think about my idea?
That would be absolutely nightmarish, I can't see what good this would bring. Imagine the packed servers, imagine trying to run away and everything is just... in your way. It would be frustrating beyond comprehension. Sorry, but no support.