First, I think that it should be noted that pirated games these days, and in the last decade, are not that different from the source. Bugs weren't really there. patches, and even multiplayer via LAN were possible even for pirates, and before Steam was a thing, it was actually more comfortable to pirate games than to buy them, what with all the DRM shenanigans we had to go through.
As for quality games you have mentioned, you are aware that all the games were released in 1999-2000, not exactly the period of time I was referring to. Let me add some more games: Deus Ex, Half life, Bugs bunny: lost in time(I kid I kid) were all released right before the great downfall of PC gaming. Yeah, 1998-2000 are some of the best years of video games, no doubt, but from then on it took a big nosedive, and besides that, I don't think the internet was nearly as popular back in the PC games golden age.
Look, I am not the one that will say Steam is the holy saviour of PC gaming, but I think when it truly became a distribution platform, it changed the field completely, and it's now almost as popular as consoles themselves. Such a thing hasn't happened for many years in the PC realm.