If you knew you could just go to a vending machine and get equipment, what would stop you from just requesting extra for your personal use? Since any new equipment comes out of my personal returns, I don't get a new keyboard just because the keyboard doesnt feel like it did out of the box -- I clean it.
If you knew that you could request a new keyboard every time you spilled coffee on your keyboard, what would keep you from carelessly placing drinks on your desk? I know that my desk was paid for with my money, so I'm very careful with regards to stuff like coasters and tall cups.
If you have to look a person in the face, you feel a greater sense of accountability (as if that person knows you requested it) and you will be less likely to frivolously request stuff.