Exactly, but when animation is made in such a way that it would accommodate adult flair, then there is every possibility of adults having good interest in watching it. One of my favorite animations back then was Avatar - The Last Air Bender. It's was such a great animation movie including its follow up - The Legend of Korra.
Yes, it's funny how some animation is of less quality. They don't give enough effort in thinking of the stories and how they're made. But if they create original and intriguing shows, I'm sure more adults will watch anime.