After all the evenings I spent as a kid at the library or on the internet trying to find stories with a character that would be like me, I can’t find any good enough reason to work on non-trans characters.
By the way, many people don’t know this, but you can ask your librarian to order books by trans authors! Metonymy Press, Arsenal Pulp, Topside Press, Flamingo Rampant… you should definitely talk to them about it, everytime someone I know did it, they were successful in getting trans author’s books in their local library. They can also get mine on http://assignedmale.etsy.com !