TNG and DS9-wise, yep, but I wouldn't necessarily credit that to Berman. Certainly not why I've bought any of it. Straczynski's work, I'm always inclined to check it out. I may end up not liking it, but there's a decent chance I will. Berman, hard to say, Star Trek aside, is there that much? Particularly in the modern era?
Re Berman's motives for not leaving. Surely there's a business case to preserve your reputation, particularly in the field of work that he's in. Sticking with Enterprise to the bitter end's not exactly enamoured him to the industry, and by the looks of it, the offers don't appear to have been flooding in.