A lot of the authors who matter most here (and there are ones way bigger then Brandon like King and Grisham) likely don't care about putting in all the work for

A lot of the authors who matter most here (and there are ones way bigger then Brandon like King and Grisham) likely don't care about putting in all the work for a few more millions of dollars when they already make 7-8 figures per book. A LOT goes into arranging print runs, managing all the extra goodies he's adding as bonuses at the higher tiers, and so on. Writers who need extra stuff to make a name and convince people to notice them is one thing. When you already make insane amounts of money it becomes less worth it. Also I wonder if less nerdy/technical fan bases than SFF would be as inclined to even get involved with Kickstarter.