It could be a limitation put by an editorial she's working with.

I'm thinking probably time considerations, she does seem to get a fair amount of work with publishers, so she probably did as much as she could between assignments.

My best guess is just that she prefers the freedom of doing original doujins.

I wish I had someone like Eri-chan who thought that much about me...

I got to the part with Nico on tv and realized it was a love live doujin lol.

Aww, this was so cute!

Cute (≧▽≦)