Actually, different mangaka have their own style of drawing manga, (and anime..) and those animes/manga are different from each other. Some animes actually aim to present the characters in a realistic way.

Generally, Anime and Manga are plain, but it can be seen as an Art at the same time.

For instance, look at the the lets pretend to be vicious game!, talking like that is somewhat an Art as well...!

Edit:

Fixed something.