In our home I had the SNES and he had the Gen so I have experience with both, later in the late 90s I got one too. The thing is I think the issue is not over or under exposure to them but the NOW.

Lets look at this time now and factor in how you feel the NES isnt played out either. All these modern so called retro indie games seem to try and match the luster of the NES and either the SNES or the Amiga/90s PC style stuff to be cool and retro both in visuals and audio. The Genesis even in the day may have looked sharp but it lacked some basic talents like transparencies or even enough colors on screen to match 256 VGA output like SNES can. The audio was a borrowed earlier arcade synth chip which sounds tinny, rough, mechanical almost while the SNES relied on nearly CD quality output and sound samples which again fits more withthe now. The style of the Gen is seen and heard by enough as out dated.

It comes down to preference but those making games that wannabe old seem to also prefer the nonGenesis look of things and go with the NES, SNES or Amiga/PC style of stuff.