What makes an RPG good?

[MoiMagnus]

Some people like complexity.

I'm doubtful of that, though it might depends on what you call "complexity".

A lot of peoples like the depth that complexity allows.
But I don't know anybody who would prefer a D&D in which every ability score is a multiple of 0.73 instead of an integer [and the modifier associated is ((N*1.37)-10)/2, rounded down, so same game balance] just for the sake of complexity.

Complexity is the cost of interesting features of a game, but it's still a cost and you don't want to overpay.