Gameplay mechanics were also a lot better with more replayability.
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!
That's some survivorship bias shit right here. I can't tell you how many shitty, buggy games I played in the days of early console and PC gaming. Even games that were revolutionary and objectively good games sometimes had game-breaking bugs, but often it was harder to find them without the internet.
Plus, don't you remember expansion packs? That was the original form of DLC.
Yeah, if a DLC isnt just content taken out of the main game (in a way that makes the main game worse) and is reasonably priced for the amount of content it contains, then it is a good way for developers to get paid for continuing development of a game after launch when it was already finished at launch.
Oh man, while I was reading the first part of your comment I was thinking of the Witcher 3 DLCs the whole time, I'm so glad that you mentioned them at the end there!
I don't see how the amount of "completeness" can even be measured. Is it really so much worse that you can buy extra fighters for the Street Fighter 6 that you already own rather than buying Super, Turbo, and then Super Turbo at full price every time? Or that you can choose to buy just the stuff you want for Cities: Skylines for half the price instead of paying twice as much to get stuff that don't care about along with it? Plus, expansions like Phantom Liberty and Shadow of the Erdtree are bigger than most entire video games from the 90s.
Except for when they did not, which was actually somewhat common.
But it also became quickly known, respectively stores stopped stocking buggy games. So in return, larger publishers tried their utmost to ensure that games could not have bigger bugs remaining on launch (Nintendo Seal of Excellence for example was one such certification).
But make no mistake, tons of games you fondly remember from your childhood were bugged to hell and back. You just didn't notice, and the bigger CTDs and stuff did not exist as much, yes.
PC:
It was just flat-out worse back then. But we also thought about it the reverse way: It wasn't "Oh this doesn't work on my specific configuration, wtf?!" but "Oh damn I forgot I need a specific VESA card for this, not just any. Gonna take this to my friend who has that card to play it.".
Counterpoint: budget re-releases of games (e.g. 'Platinum' on PlayStation) were often an opportunity to fix bugs, or sometimes even add new features. A few examples:
Space Invaders 1500 was a re-release of Space Invaders 2000, with a few new game modes.
Spyro: Year of the Dragon's 'Greatest Hits' release added a bunch of music that was missing in the original release.
Ridge Racer Type 4 came with a disc containing an updated version of the first Ridge Racer, which ran at 60fps.
Super Mario 64's 'Shindou Edition' added rumble pak support, as well as fixing a whole bunch of bugs (famously, the backwards long jump).
Those are just off the top of my head. I'm certain there are more re-releases that represent the true 'final' version of a game.
That's the exception rather than the rule. If you have the opportunity to make some changes in a new batch, why not take it?
Generally, when the game was released, it had to be done. If there were any major bugs, then people would be returning their copies and probably not buying an updated release. It'd also hurt the reputation of the developer, the publisher, and even the console's company if it was too prevalent of a problem.
I don't think anybody I knew ever got an update to a console game without just happening to buy v1.2 or something. There were updated rereleases, but aside from PC gaming, I don't think most console gamers back then ever thought "I hope they fix this bug with an update".