Customizability. I want to be able to put my stuff in there, without the case design telling me I can't. Far too many cases say you can mount a radiator on top, yet when you do, you need ½ size fans or they interfere with the ram/motherboard wiring. If I want to remove all the hdd cages, I should be able too without having to drill out rivets. If I want to change or remove cards, I'd like the covers replaceable not cheapo 1 use snap outs. I want to make that pc mone as I see fit and not be restricted. It's not really a hard concept to grasp, yet it's seldom accomplished.