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!
A couple of points.
We didn't need online access back then, we had LAN parties.
Most of the time you didn't need updates, because back then they were much more diligent about making sure a game released without bugs. Yes a few existed, but much less than what you see in today's games. A showstopper bug was death for sales, since it couldn't be fixed inexpensively.
And those instruction books, especially if you are into the artistry that they put into them, is sorely missed, truly.
Hmmm, I don't think that I can agree with the point about older games having fewer bugs. In my experience, 2000s 3D games are riddled with bugs to the point of becoming unplayable in many instances.
There were some pretty bad bargain bin releases, and a lot of games had glitches but I can't remember any game from a big company that released with a critical bug. I do think today companies are much more blasé about releasing games with serious issues and patching it later.