There are thousands of books/games/novels/comics....what more do you want? At this point its almost not worth making anymore movies, because then a lot of stuff is gonna be switched and turned upside down.
yes there are books and comics but like GL said, anything beyond the 6 episodes is "made up" meaning it doesn't happen. so if he were to make a sequel trilogy, all of those books and comics would go down the drain being meaningless to continue. that may be an added reason to him not doing the sequel trilogy. and fans rather see a star wars movie or show any day rather than read a book. but your point is fair, plus the star wars timeline seems to be going backwards than forwards. It would seem the further the franchise goes back in time, the better it gets.