I can't stand most retro games, because modern games tend to do everything better in terms of story, gameplay, polish and production.
However, I do admit there's one thing that retro games do better: they allow much more in game decisions. Just compare Fallout 1 to Fallout 4 and you'll see what I mean.
Baldur's Gate is also an excellent example of this - tonnes of loot, skills, stats, classes, characters and tonnes of side quests or ways to advance in the story. It's one of the retro games that I still enjoy and I recently finished it on multiplayer.
RE: The appeal of retro gaming