I see it more as Nintendo hit the sweet spot with both the NES and SNES Classic systems. Prior to those Nintendo didn't really do massive game compilation discs or mini consoles. Yeah there had been a few small game collections (ie: Mario All Stars, the Zelda Gamecube one) but nothing that rivaled the amount of games that other mini consoles from say AtGames offered. And unlike AtGames the offerings from Nintendo has great emulation and solid good controllers (short cord on the NES Classic aside).
So how did this effect the Genesis Classic? Well for one we've had many of these same games on other mini consoles and compilations for decades. There's little new here on the Genesis Classic to make it worth buying. Yeah it has the obscurely little known version of Tetris but that isn't really worth bragging about since Tetris is on just about every single dang thing ever. Even the Atari 2600 has Tetris on it (even if it's named differently... it's Tetris). Not to mention how many people just looked at the Genesis Classic thinking it's another AtGames product since AtGames made how many of their own Genesis flashback systems that all were trash?
And speaking of AtGames... I did find the recent Legends Flashback (the 100 games version) at Walmart for around $8. Honestly for that price it's a solid pick up. AtGames has upped their game a bit recently. Controller is pretty decent if a little clicky but still works pretty well. Game selection is decent. I had a good few hours with it and enjoy it. Worth $8 easily.