That's a really good question.
And the answer is this: those people are idiots.
Let me break it down for you. Tyler Black is absolutely talented in the ring, he knows how to work, he has a great look, basically everything you listed. Granted, he may not be able to work entertaining 60 minute matches yet, but is that really something you can hold against him? No, I didn't think so either.
Black is only 24 years old (I believe), which makes his accomplishments even more amazing. He's got all the potential to be a huge star in the wrestling business.
The only reasonable complaint I keep hearing is about his mic skills.
You wrote he's great sometimes, but I have to disagree. I just cringe every time he starts talking because it makes me uncomfortable to watch and listen to him cut a promo that sounds like he either memorized it or is reading it off somewhere. Honestly, I do see a slight improvement though.
Also, since when have mic skills been uber important in Ring of Honor? That's right, they never have. As long as a guy could wrestle, the fans would love him (very simplified, but you catch my drift). And we know Tyler Black can wrestle.
So why exactly would people dislike him?
I think you answered the question yourself, OP. Ring of Honor fans are no marks, at least not in the traditional sense.
Tyler Black is pretty much a babyface; he's always portrayed as the good guy. Even when he's portrayed more violent, more aggressive, etc he is still more of a face than his opponents (until now).
ROH fans are no marks, therefore they don't fall for the babyface shtick. Quite the contrary, they don't like or hate it. Many of them feel like it's the cool thing to do to like the heels and dislike the babyfaces, therefore they dislike Tyler Black.
Pardon the generalisation, I know not every ROH fan is like that. Still, it is the only reason I can think of. And that reason is bullshit, which is way I say those people are idiots.