Ignoring the lack of updates if the game is buggy, games back then were also more focused on quality and make gamers replay the game with unlockable features based on skills, not money. I can’t count the number of times I played Metal Gear Solid games over and over to unlock new features playing the hardest difficulty and with handicap features, and also to find Easter eggs. Speaking of Easter eggs, you’d lose a number of hours exploring every nook and cranny finding them!
Glitches then: Quirks that make the game more fun, or maybe a bit weird. Anything damaging game progress is usually rare.
Glitches now: The game might not work, or your save might get corrupted, or maybe it’ll wipe your hard drive.
Mario games are usually pretty robust, but if we look at the Pokemon games, we have a perfect example.