Well, it's the sad truth that games like this actually sell. That's why the DS has so many of these types of games. Naturally, anyone with half a brain and/or a bit of gaming savvy hates them, but there are many lame-brained and non-gaming savvy people out there. Then there are parents, who shelter their kids from the "good" games and all they get is this crap. Those poor kids just don't know any better, so you really can't blame them, only feel sorry for them.
And then, separate from the above paragraph, are girl gamers. They have radically different tastes in games, especially at a young age, before they leave their "princess" phase. For whatever reason, call it a genetic defect if you will, girls have an affinity for horses. As a guy, I cannot understand this affinity, but it definitely exists.
Despite how much we don't want it to be, the DS IS a kiddie system, and that's what it caters to first and foremost, so we get tons of crappy games such as this one.
Veteran gamers only get thrown a bone occasionally, of which, this game is NOT one. It's sad and pathetic, but the truth.