A difference would be that then they were "sketching in" the details of a planet with a few polygons whereas now people want everything nearly photorealistic with every grain of sand being individually textured and actual space pelicans flying around and maybe laying eggs with persistent pelican chicks that can evolve and contribute "deep gameplay".
I'd say the main difference, beyond the detail of the geometry, is multiplayer. Having persistent spaceships and NPCs you can follow around is easy in single-player. Doing it in a multiplayer environment is extraordinarily complicated.
Personally I think they could have made a much more engrossing game if they'd stuck to single player, but I'm not sure things like this forum would exist if they'd done that. There wouldn't have been a community.
I'd say the main difference, beyond the detail of the geometry, is multiplayer. Having persistent spaceships and NPCs you can follow around is easy in single-player. Doing it in a multiplayer environment is extraordinarily complicated.
Personally I think they could have made a much more engrossing game if they'd stuck to single player, but I'm not sure things like this forum would exist if they'd done that. There wouldn't have been a community.