Is it Because Their Ponies?

[mlp4me]

I think they're popular because Hasrro is just amazing at marketing!
Why not have a cartoon and stock it full of characters that you can watch on TV and then buy and play with?
All those places the ponies visit, dream castle, satin slipper sweet shoppe, nursery, paradise estate... how genius was it to also be able to purchase these items too.
Yeah, I guess we're suckers for pretty plastic things that have hair...

[ZeldaTheSwordsman]

There's always been something appealing about equines to me, especially sentient fantastical ones. I love "The Last Unicorn", and I also love MLP.

[Betelgeuse]

there's something about equines...
But other than that I think it was all the love and attention Hasbro put into the franchise

[kittybethy]

There are so many reasons to love ponies! I can't pick just one!

[LadyMoondancer]

I think that although the cartoon certain provided a sales boost, it wasn't responsible or necessary for the line's success.   The large, hard plastic "My Pretty Pony" sold over a million units without advertising--that was what inspired Hasbro to shrink them down into the related My Little Pony line.  Then they released the original six ponies, and with nothing more than a few TV commercials they were even more successful.


I never saw much of the TV show as a kid and I don't think I was unusual in that.  (Remembering that these were the days before everyone had a VHS, and when there was certainly no Youtube.  You either happened to catch the cartoon when it played or you didn't.)   


In fact, I had never even heard of My Little Ponies when I got my first one, Moondancer, as a gift from my grandmother.  But I still walked around the house hugging the unicorn, repeating, "At last, all my dreams and wishes have come true!"


There's just something magical about ponies . . .

[SheRa-dude]

Ditto with Fairy Tail Birds, which were basically MLP versions of birds.

I always felt like they made a mistake marketing these birds as separate from MLP. If they had included them in the MLP line, for ex. selling a pony with a bird, both in the same design - it might have caught on more. I loved those birdies

And to answer the OP's question: I definitely think it has a lot to do with them being ponies, but it's much more than that. There were/are other toy horse lines that never got as successful as MLP. It's the totality I think; horses, colors, the world created around them, the diversity, the logo,...
And then there is also the final element in the mix: the mystery of it all. Every now and then, something is created that seems to just catch on and fit right into that niche, while other similar things, though equally thought out, just fall out of the boat for some reason. MLP is one of those lucky things I guess.