Optional yes, but they're core to the system & it's future. It's a smart move in many ways, it means that they can abuse their userbase as free advertising. Allow me to explain:

ATM if you want to upload footage from a console you need to have capture hardware & depending on what quality you want (and who doesn't want the best?) you'd have to have a fairly meaty PC on the other end of it. Even stand alone capture devices require some form of editing...

Sony are cutting that need, it's basically the biggest free advertising method you could make. People will be uploading images & videos constantly since it's essentially at the push of a button.

Add their wonderful patent on locking a disk to a console, which we all know is coming no matter what BS they've spouted (you don't patent something unless you intend on using it; tick tock tick tock...) and you've got the whole shebang.

People advertise a game for them with video & image, users have to go & buy new copies, Sony rake in a fortune off the BD licensing that's attached to every commercial disk. They'll also be raking it in off the other machines that have Blurays.

Depending on how all the video copyright crap plays out you're looking at a machine that'll become a favourite with LPers etc, along with the every day gamer wanting to show off.

As I said, It's a smart move.