http://www.tomshardware.com/news/PlayStation-VAIO-Sony-Optiarc-OEMs-Optical-Drive,17209.html
I can understand their reasons, optical devices are all but given away these days so I can see why there's no profit in it for them. I personally think there's very little mileage left in optical discs anyway. I'm sure that even operating systems will be delivered via the net soon enough.
Prob what MS is planning with Midori.