That could work though. Remember, the iTunes store came after iTunes itself. In the early days everyone ripped all their music off CDs. However, then the convenience of the iTunes store took over. If Apple lets people rip all their DVDs then when people come to add to their collection they'd be far more likely to purchase new films through the iTunes store. I'm doubt many people will rebuy films they've got on DVD anyway although people are far more likely to rip their DVDs if iTunes supports it and with time their video collection could move from the DVD shelf to iTunes like the CD shelf has moved.
Plus ripping your own DVD might make the Apple TV some what useful. Right now I see the Apple TV as pretty over price and rather worthless. Even after this the apple TV will still be pretty much that way but it would increase sells of it at least. For me I would use that to import DVD then stream it to my 360.