In my opinion it looks like they are mocking the manga and anime style. I've seen it in a lot of cartoons (Kappa Mikey, the Fairly Oddparents movie Channel Chasers, Mad tv). Or it could just be a poor recreation of the anime/manga style. (Sorta like my art) As for why, I assume it is because more people are watching, reading, and drawing anime. I guess they hope that it will be more popular then the original. Also they probably want a larger audience.
As for the anime X-men trailer, I might look into it once I have some spare time to have a true opinion of it.