The gamepad I'm using works in emulation station, but doesn't work when I'm in the ROM. apparently it's due to thi issue: https://github.com/RetroPie/RetroPie-Setup/issues/564
I still haven't fixed it because I can't bring myself to screw around debugging a linux system after a long day of coding.
So, I have no doubts that many people can and should use a retropie. But, my childhood gaming experiences didn't involve the location of the RetroArchs/config folder, and I'd really rather my attempt to relive that experience as an adult didn't, either.
It did however play PS1 games using a RPi 2 almost perfectly using the original 240p resolution of the games.
Plenty of people have moved on to better technology and more sophisticated games, but let's not assume every player would get bored of these true classics.