I can't say or guess how large a percentage of fans blame Berman for anything, nor am I going to defend anyone bashing anyone else. However, when Braga was on the college lecture circuit after Enterprise was cancelled, he once decided to gauge the crowd by asking (and I paraphrase) "how many of you think Rick Berman and I killed the franchise?" Hands went up. Now, three things:
-while it doesn't say if there's a majority or a minority that people hate their work, it does show numbers sufficient enough that warranted Braga's attention
-times have changed since Enterprise was cancelled, so whatever numbers there were most likely shifted one way or the other (I *think* Braga hit the circuit in 2005)
-admittedly, Braga was a good sport for even daring to ask that question
Also, when Garrett Wang was moderating a DragonCon 2010 panel of the TNG cast (plus Quark, for some reason), Frakes asked how did people feel about the Enterprise finale, to which Spiner deadpans, "The same way they felt about Nemesis." Laughter breaks out obviously, but when people complain about Berman, those two particular works are usually shoved to the forefront by his detractors (fairly? unfairly? Not really a concern?).
The point being is that whether the number of Berman bashers is a majority or a minority, it's still a rather sizable chunk of the fandom to have such an effect. If it was a small minority, then the question is "how small?" and then after that, "if it's that small, how and why are people -- both his detractors AND his defenders -- still talking about him to this day?" Essentially, why do his decisions from years ago still make the stuff of today's articles that fuel modern fan discussion? Why would he even feel the need to address his detractors so long after the fact?
Well, since you're INSISTING I provide answers, I'd have to say I-
(those are rhetorical questions, don't feel pressured to respond!

)
Oh. Never mind, then.
But seriously, excellent post. And that's interesting, that bit about Braga asking that openly... I had no idea he ever did that. Whatever I might say about him as a writer, that takes a decent bit of guts. And actually, I don't even
hate him as a writer. More than anything, I just think he works best when he has a strong co-writer. He has some really awesome conceptual ideas, and excels in coming up with stuff that's really out there. But when the actual
execution of those ideas is also left up to him, that's when things fall apart. He needs someone who will bap him on the head with a rolled-up newspaper whenever he goes off the deep end; properly reigned in, his base ideas are often excellent and can be made into compelling episodes.
As for Berman... I still maintain that the idea that he
wasn't trying his best to make what HE thought was a strong product is preposterous. Him and everyone else involved with Trek, really. Bad decisions, bad judgment, and ultimately bad show running =! intentional, malicious sabotage or uncaring laziness.
He did do a lot of good for the franchise, but he certainly did his share of bad for it, too. But consider Voyager. Was he responsible for some of the overall creative decisions that kept the show from being better than it was? Sure. Some of them, however, were the network's ideas, not his. But he only
wrote 8 eps (and all of them co-written with others). One of VOY's main problems was simply lousy and often inconsistent writing. Rick Berman cannot be blamed for everything. He had a hand in creating the problems, sure, a fairly large hand. But you can't just say "Without Berman, things would have been just fine".
He did seem to be more involved with ENT than VOY, especially in terms of writing, and what I saw of ENT painted it as a far worse show than VOY on the whole. So perhaps he can take more of the blame for ENT in particular, but you
still can't just stick the entire thing on one person's shoulders - ANY one person, not just Berman. More often than not when it comes to a television production, failure - like success - is a team effort.
As another example, take Nemesis. Does Berman deserve blame for his role in bringing on Stuart Baird, for his portion of the badly-written story, and for allowing Spiner to have such a large hand in writing it as well? Sure. But Baird still did an awful directing job, and the vast majority of the story sucked, not just the parts written by Berman, and Spiner - while a great actor - showed that he probably shouldn't be doing much writing, at least not for Trek. Again, you can't just throw EVERYTHING at Berman's feet, and say "If it weren't for
that guy, we woulda had a good movie!"