For what it's worth, I'm in favour of having the option to lock my cam, if only because I like to operate mine on a like-for-like basis.
I have a few regular buddies who I like to cam with, and some days I just like to log on and have some private, mutual fun with one of those guys. I don't always feel like putting on a show for the whole room. Sometimes I do, but it's nice to have the option!
But my real problem is with the guys who NEVER open their cams. And in my experience, they're always the same guys who want you to open your cam.
I don't think its unreasonable to expect a bit of give and take. If you're NEVER gonna let me see your cam, don't think you're gonna get a look at mine.
Might sound selfish, but thats just my opinion.