Am I misunderstanding, but that I cannot access certain parts of my PBS account until I rate 752 books?  

What specific areas are you talking about? Books can't be put on your Books I've Read list if they aren't rated (I know that was changed since i joined), but other than that, I can't think of an area you might not be able to access.

That is something I have never heard of -- I have been here 3-1/2 years and that is totally new to me. I think you must have the wrong end of the stick on this one.

Back when the BIR list changed (early 2008), in order to keep the books you had read on your BIR list, you had to rate them.   So yes, in away you are forced to rate them to keep them on your list.

I just went through and gave like a 5 to all of them to keep them on the list.  You can adjust ratings so when I come across one I feel I need to reduce then I lower the stars I gave it.  I kind of feel like when they did that it kind of skewed the star ratings. I'm sure I'm not hte only one that just gave a random rating to all their BIR books because it had been so long since they read them and they just wanted to keep them on the list.