I can agree, but sometimes gameshark or AR codes create a fun experience, depending on the game. Platformers such as metroid or Mega Man, RPG's or anyone sort of open world games. It's interesting to see what stuff is STILL in the game data even though you can't see it.
Some games have Dev rooms still hidden inside, I think Chrono Trigger is one of them. I know Zelda Ocarina of Time has many many secret rooms, new ones still being found to this day. I'm also positive there's a bunch of hidden things in games like Super Mario 64, Mario Sunshine, and so on. AR codes aren't all bad, depends on how you use them. Cheating with them just to cheat is pretty lame though