Here, let me give you a simple solution :
Let people do whatever the hell they want.
There are still quite a number of popular R6 games, aren’t there? R6 is not “better” than R15, and neither is R15 “better” than R6. It’s like comparing apples to oranges. Sure, it has more joints, but it takes away the feeling of creativity to make unique poses, that can only be done using R6. This is not an “upgrade” from R15, it’s just a feature.
Let people do what they want, as long as it’s good. A well made R6 game will be way better than a poorly made R15 game. It’s a simple concept to grasp.