Mark Delsing You and I might look at a Kickstarter with a brand new system and think “oooh, cool, look how thoroughly the system and setting are integrated!” but there are a lot of people in the world who would look at the same Kickstarter and think “looks cool, but I wish it used Savage Worlds/Fate/whatever.”

I’m not trying to trivialize the importance of system.  I agree with your sentiment.  But many roleplayers are just looking for something that does skills/abilities plus a dice mechanic, and then get out of the way and lets get on with things.  To them, familiarity is far more important than integration between mechanics and setting/theme.