Every single thing about it is what makes it a "show for little girls".
You like it because of the surrounding hype and the fact that it makes you think you're special. That's cool. I have other ways to express my 8-year old girl-side and we all do somehow...

...It's just that we all don't just conform exactly to what a new clique of people are doing at the time. I mean, doing that is kind of a combo thing I guess, because it's an easy gateway.
Do whatever makes you happy, but please don't push it on people like most "bronies" do. It's fine if you like something, I like things too, but I don't try to prove how ok it is for me to like it and that other people should too.

That first paragraph is amazing too. You don't think kids relate to characters with responsibilities and defined characters? That's my only gripe with this, "bronies" just praise it blindly and don't actually realize that most kids shows are written that way. In order to resonate with a young person, you definitely need that, in large quantities. The reason why you don't watch those shows is because they just don't have the same internet hype buzz around them.

I mean, this is just the late 90's anime craze all over again, isn't it? I had friends who had older brothers who watched half-subbed Sailor Moon episodes religiously and when it finally came here on TV - it was just any show for 8 year olds with some attached stigma that you were special if you watched it.

I've seen it. It's not bad or anything - but it's exactly like other shows. You can like cartoons for kids all you want, don't try to make it so god damn special to feel better about yourself.

I think part of what really defines 'MLP:FIM' as a "kid's show" is its educational content. I haven't seen every episode, but nearly all of them are concerned with teaching basic morals and messages typical of children's programming. As I said, it's well-written and not at all stupid or condescending, but the storylines are still relatively simplistic and accessible, the songs (which feel obligatory) are pretty light and fluffy, and apart from a few subtle pop culture references, it never really reaches the level of subversiveness of a show like 'Animaniacs', which practically serves as all-ages comedy rather than age-specific entertainment.

The characters don't have to "act young", I see them as being very relatable on a base level as they cover the broad range of personalities in children, primarily young girls: the tomboy, the bookish one, the shy one, the girly one, etc. The fact that they behave more on the level of young adults seems intentional in a show for a younger audience: kids emulate older kids, and the characters effectively serve as role models. Kids are a lot more complex than you might be giving them credit for, especially at the crucial developmental ages of 6-12 (which is The Hub's official demographic). Likewise, they aren't stupid: they may not catch the obscure pop culture references, but their comprehension level is much higher than people realize, considering all the rock-stupid kid's "entertainment" you often see in the mainstream.

Beyond the superficial elements of ponies and bright rainbow colors, the fact that all of the primary characters are female is pretty much a good sign the show is "for little girls". I think it's broader than that, since it doesn't tread out the typical "little girl" show stereotypes of emphasizing fashion and femininity but rather seems to deal more with the concepts of relationships, friendship, emotions, etc. regardless of whether or not one conforms to their typical gender behavior. I could easily see it appealing to open-minded young boys based on the messages and even the humor alone. If it was on when I was in elementary school I likely would have loved it...probably because I could have immediately identified with Fluttershy. :-/

Adventure Time has a passionate audience of both children and adults "who are drawn to the show's silly humor, imaginative stories, and richly populated world."

Honestly, I was never a huge 'Animaniacs' fan, though likewise, I can admit the writing (and the music) was fantastic. The only Amblin cartoon that's stuck with me since it originally aired was 'Freakazoid!'. That was arguably aimed towards a slightly older audience, but it's still just as awesome funny now as it was back then. That's the best kind of "kid's show": the humor is goofy and accessible enough that young kids can enjoy it, but it's genuinely funny and clever enough to appeal to older audiences. 'Freakazoid!', for example, worked by subversively satirizing the conventions of the superhero genre, rather than just overly relying on tired pop culture parodies (though it did that a little bit, too). Same with 'The Tick'.

'Adventure Time' (and 'Regular Show') is written by twentysomething hipsters for twentysomething hipsters. Those shows are just one big smirking in-joke. 'Regular Show' is a bit more tolerable, but 'Adventure Time' seems to exist solely to sell shirts at Hot Topic so you can wear them to the next electro-pop house show in Brooklyn.