Rings of protection IMHO have *negative* influence on BG game play:
First of, they add passive protection. No interesting game mechanic there.
Second, there are plenty of these things on the main route of BG, so there's no push towards having to hunt them down in exotic places. They thus don't instigate any 'drive' in you.
Third, they make BG easier. BG is plenty easy as it is, so that simply translates into: more boring.
Fourth, and worst: they make magic armor mostly pointless. Which is sad because magic armors *do* reside in exotic places which thus really could instigate you to go on adventure to hunt them down. If they were actually useful, that is. Which they aren't, because of protection rings...
Therefore, I have added protection rings and necklaces on my long list of banned things in BG.
Furthermore, I have decided that I won't sell these items when I find them. I will go to Beregost and simply dump them in the streets! Muahahaha!
(okay, that's not so evil.. but still!)