I'm in a weird position since I've loved cartoons in general as a kid (courage the cowardly dog, martin mystery, etc.) and continue to love them as an adult. While I don't jump up and down with glee or catapult over a couch to catch my favorite show as I may have once done, I think that the Bronies who do that are also as few and far between. It's kinda like the Rick and Morty fandom. There's some people who are laughably arrogant, but a majority of the fandom just appreciates the show for what it is and what it gives us and that's about it. I think Bronies get a bad reputation for being man or woman children and that's not really fair, especially since like Bronies, Littles will often feel happy when watching cartoons. For those of us who haven't lost that love of them, it just takes us back to a simpler time. Away from the responsibility of adulthood...and that, in essence, is kind of what being a cosplayer/otaku (and, yes, a furry) is as well. It's all about escapism. I'd just like to not see my favorite child friendly pony with sausages up it's butt, please and thank you google images.
So in short,
I think the hatred or disgust with bronies isn't much different from any other fandom.
It's all steeped in misunderstanding and misplaced judgement (and a few bad apples).
Plus, google searches don't make it any better.
I typed in "brony" and hit enter, and that's what popped up as the first result.
Those first few pictures....yikes.
No wonder outside people have bad misconceptions.