It always starts out with the attempt at keeping the "flavor" of the original.
But it doesn't stay that way long, no?
Star Wars
Star Trek
Warcraft
Starcraft
COD
Battlefield
Mass Effect
Halo
Dr. Who
Ghost Busters
And on and on and on....
Each franchise falls when people who were once anethma to the core principles start waving the cash that could be brought in.
Every man has their price. And those that would seek to destroy anything and everything are willing to pay whatever it takes to rob joy from others.