Opinions about making the forums open again for non-registered users?

Before the relaunch, the forums (and some other parts of the site) were accessible by non-registered users. Let's call them lurkers. I saw that some older posts found lots of fans and readers, and ultimately brought them to sign up and be part of the community. I'm against making everything open to non-registered users, e.g. I don't want to show profiles and pictures to non-registered users or even google. Do you guys have any opinion or feeling about this? Maybe some ideas about new forum categories?

I think it's not a big hindrance to create an account to use this site so why should someone lurk? On the other hand, if someone wants to read stuff he might create new accounts en masse as that person forgets his login for his "trash account". So there might be a lot of dead accounts because this site is not open for lurkers. Maybe you could make the users choose wether their contents should be visible for lurkers or not. Maybe like a checkbox for the account settings.

Deleted

No, no. I mean all registered users. The part about ghost accounts is also a good point to keep in mind. Ultimately I don't want to let search engines scrape out our profiles and their pictures.