Here's a provocative thought:
RPG games have boomed because they're the descendants of point&click adventure games. I'd like to have the name "cRPG" changed to "Adventure". It describes much better what the game is about, the majority of players doesn't care about role playing, and many cRPG games don't even support that. Diablo is often called Action RPG for some reason despite not offering a choice at all, the story always unfolds in exactly the same way.
Anyway, old point&click games were usually about a story. Now cRPG games are the vessel for that. Exploration is also crucial to both genres, I know of no cRPG game which takes place in the same area, where variety comes from changes, events, new people arriving rather than unlocking new zones. Baldur's Gate 2 and Planescape: Torment are a good example of what I'm talking about - both have big cities, but what you're really doing is getting access to new areas within them.
Anyway, old point&click games were usually about a story. Now cRPG games are the vessel for that. Exploration is also crucial to both genres, I know of no cRPG game which takes place in the same area, where variety comes from changes, events, new people arriving rather than unlocking new zones. Baldur's Gate 2 and Planescape: Torment are a good example of what I'm talking about - both have big cities, but what you're really doing is getting access to new areas within them.