In my honest opinion, it's just like any other fandom. It has it's good, and it has it's bad. However, it isn't the first show to be targeted to girls that has a larger audience.
In my eyes, Powerpuff Girls is one of the pioneers for that. It still has a fandom that's still strong to this day, and it still, in the end, did seem to be targeted towards girls, or was at least viewed as a feminine show.
However, I will say that the MLP:FiM fandom helped popularize it even more, to the point where it's become normal in the Internet culture, as well as beginning to work its way into modern society. Not to mention the fact that there will most likely be more shows like it, with the later generations of MLP going to attempt to appeal to the larger audience, as well as other shows trying to use it's formula.
But anyways, it's just like any other fandom, or at least in my eyes. You have the AMV (or in this case PMV) makers, the artists, the musicians, and so on. The only reason it's viewed on as bad is because the Internet likes to target certain fandoms at a time. It's not like the MLP fandom is the only one to suffer this treatment, I mean look at the FNaF fandom, or the Sonic fandom, or even the furry fandom. All of those are popular to dislike. As for a reason to why, well I have a few ideas for it in mind.
People tend to put their opinions in front of any logical reasoning, which affects their viewpoints on certain things. This is what fuels that toxic minority of our large community. However, people outside the community have this to, and well you always see them complaining about how 'horrible' this community is, while being a complete bigot. They fail to see the fact that this community (and the aforementioned ones) are just like any other, and the only look at the bad.
Another reason is because people don't understand the popularity of the show, or just don't like it. This sort of ties in with the previous reasoning, so just consider it an add on to that. Anyways, people who dislike the show itself or are just neutral on it tend to judge an entire group of people just because they don't understand it.However, that isn't to say there aren't people who don't care for the show but don't judge the fandom, but I digress.
I also should mention stereotyping. There's people who had bad run ins with the toxic fans, and judge the entire fandom based on a few bad eggs, which also isn't the right way to go.
I could go on and on about this, but I think you get the point.
tl;dr: A lot of people are bigoted and completely over exaggerate on how 'bad' the entire fandom is. They also tend to stereotype everyone who's a part of it because of a few run ins with some bad eggs. Also, to answer the original question, nothing much really, it's just like any other fandom in my eyes.
Although take everything I said with a grain of salt, since it's just my opinion, really.
Edit: Wow, I got so into my rant I forgot about the original question! My bad!