Because Apple doesn't support illegal activities. YES ripping DVDs you own is illegal.
Who said anything about illegal activities?! Like I said, Apple TV requires you to have a computer, with iTunes turned on at all times. What a waste of energy. God forbid you've got one of those new iMacs where they produce a ton of heat.... or older Mac Pros which are noisy and also produce a lot of heat.... all that just to have the Apple TV play a movie?
Ridiculous.