Here's a basic rule of thumb. If :
A) you are, for whatever reason, thinking that "XXX" people are "YYY"
B) "YYY" isn't as much of a straightforward consequence of "XXX" as "White supremacists are racist people"
Then you are wrong.
For the same reason some LGBT people will react to disapproval and being told that they should be ashamed of their sexuality by claiming their Gay Pride, peer pressure is the main reason why some MLP fans will identify themselves as "bronies" (which isn't necessarily a bad thing). Just like the Gay Pride, this may annoys people (that wouldn't actually mind one's sexual orientation) and only strengthen the opposition. Then what happens whenever someone criticize it ? Most MLP fans, even those identifying themselves as bronies won't care. "Stop liking what I*don't like" is as old as the world, why bother ? Still, any sufficiently big group of people will have its load of [insert adjective] people, and as always, they're the loudest ones.
I've seen a few of them in forums or Youtube comments, but for the little time I've lurked Ponychan, I can assure you the complete opposite is true. I saw a thread from a brony discussing the reasons behind this fandom, another one from an outsider in investigation, a few failed trolling attempts, amongst other insightful discussions. The general consensus seems to be that MLP isn't the best show ever, but attracted them as a haven amongst this world's cynicism, and then the community took them over. Someone asked how to "convert" his friend, and literally everyone told him he shouldn't to try to shove it down its throat, as MLP just isn't for everyone. If anything, I could understand people saying they're overly goody-goody, but aggressive...*wait, what ?
Still, I agree that it seems way too much for just a TV show (but then again, every single fandom makes me feel that way...).
As for me... This report from some guy who talked to the show's director says it all. For the record, the decision he's using as an exemple here was made long before the show even aired, when they had absolutely no idea the show would get any kind of periphery demographic :
All the great little "bits" that they keep throwing in—from high-quality animation that they sweat and sweat until it's perfect, to Sondheim-homage musical numbers, to outright references to things only adults will get—are basically the Studio B staff just entertaining themselves rather than anyone in the audience. Jayson said that what makes this show so great is the result of a million little wonderful surprises, occasions where someone assigned to some task just comes back with something that goes way above and beyond the expectation and throws everything into a whole new and awesome light; and all those things sequenced together inevitably ended up making the whole show just that awesome. Hasbro giving them a very loose rein and generally a policy of "why the hell not?" was what brought it all together. Case in point: Discord. Discord was a character straight off Lauren's pen, because apparently she'd been bingeing on Trek:TNG lately at the time that script got written. She decided to play him just like Q, because why the hell not? She'd originally planned to have Discord voiced by a De Lancie soundalike; but then during one of the meetings, someone (Jayson said it might well have been him) just said, "Why don't we just try to get the real guy?" Sure it cost money, but Hasbro said why the hell not? And John was free, and he was game, so there's our Discord. Why the hell not?
So as to who they're performing for, it's not us, it's not 6-year-old kids, it's themselves. They're just doing what they think makes the show as great as they can, to entertain each other as best they know how. In other words, the creative team on this show really is just having that much fun making it. Best thing I could ever have heard.
I have a soft spot for anything made with this state of mind, and I could feel from the first episode I watched how much the animators f***ing loved their jobs and put their heart and soul into it.