My first experiences with anime were with Toonami (back when Moltar was host) with Robotech and Sailor Moon. To the dismay of one of my friends, my later anime interests would follow the path of Sailor Moon rather than more mecha anime like Robotech/Macross. Once I learned WHY it looked different (I was...10 at the time?) and where it was from, I decided to look further into it. A couple years later, I discovered manga with an assortment of Clamp works, and it kind of snowballed from there.
And as for why... well, aside from the fact that I don't see the need for an actual reason other than I love it, I suppose it would be because the humor, stories, and characters are more enjoyable to me than that found in most American television shows. That, and I've become spoiled and find a lot of stateside cartoons to be horribly drawn with ugly character designs.
And there you have it!