Like I said, I don't know why the fanbase is so religious about it. Like most of us don't wear our interests on our sleeves. But Bronies celebrate their fandom to rather large extents. There is definitely some kind of statement in there and, though I don't doubt that some people genuinely like this cartoon, I highly doubt all of them love it to the extent that they say they do.
I mean saying you like dumb or contradictory stuff for the sake of being ironic is a pretty popular thing to do these days. Like high school students who claim to still watch Sesame Street and enjoy it. On an objective level sesame street is extremely monotonous and boring television, even for young kids. I couldn't stomach it as a 5 year old and, now that I've 15 years more exposure to better television, I probably wouldn't even be able to look at it without vomiting.