What was so immersion breaking about him? He seemed to react to his surrounding in an appropriate manner, and knowing nothing about DnD, I always assumed Boo to be a normal hamster, whom simple-minded Minsc imagines to be something more. The closes thing to immersion breaking I can think of, are things characters say when you click on them - "Yes, oh omnipresent authority figure?" - no doubt a left over of RTS genre, and not the best fit for BGs. And definitely there were things I couldn't stand - like the taking sword.
The fact that he is a simple-minded rashemi ranger who talks about a "Miniature Giant Space Hamster". Not just a magical or planar hamster, that would be just silly and cringy, but a miniature giant hamster from space would only make sense if Minsc was somehow related to Spelljammer setting and space stuff, not a simple Rashemi ranger.
