>>15381969
I think there's a big difference between stuff like Game Genie, actually editing the game, and having codes done with button presses. But as has been said, the stuff you unlocked from those codes became DLC or just got removed entirely. I'd say part of this is because a lot of genres that used those codes extensively have disappeared, but of course they haven't disappeared entirely, yet the cheats have.
Also, a lot of great glitches in the past weren't fixed in later revisions. Combos in fighting games are a glitch. But nowadays, yeah, they'd probably get removed.
>>15382169
I get why using cheats that make the game easier would disable achievements, but yeah, not being allowed to use costumes or whatever is dumb. That said, those other cheats still add a ton of replay value to a game, even if I'll wait until I get all the achievements to use them. Or hell, put in achievements that you get for doing specific things with certain cheats on.
What achievements really did away with was unlockable content. Why add extra content to the game when you can just give the player meaningless points instead? Then you can sell that content to them as DLC later.
And the best part is that if you don't have those cheats to add replayability, and they are a bad goy and don't shell out for the DLC, then they have less to play, so they'll buy your next game faster!