With such crappy drawings, it's hard to tell if someone is supposed to be male or female anyway...

For that reason they tend to give characters silly hairdresses. A big bunch of people is used to animate those characters, and so they have to draw in a generic way to mantain consistence, but as in Japan it is common to use slaves for drawing comics (some of the most popular, like Rurouni Kenshin, I think is spelled that way, was transalated as Samurai X in some places, or Gantz are barely drawn by the author) and have pressures to do it quickly they end losing any style and draw in that too simple and silly way.

It's a bad style, but I suppose it's popularity is caused for not needing to know how to draw for drawing that way.