There are a few lost souls in SoLD that like to roleplay... and the best shot at total immersion that you seem to have nowadays is Neverwinter Nights.
While roleplaying and immersion were intense for some of us, we're not currently playing - some are pretty eager to try out Neverwinter Nights II though as soon as it is released!
Neverwinter Nights is a MORPG with a unique server concept - the game comes with a toolset to create, and highly customise, your own world. So all online servers to play on are player-run. In consequence, playing is for free, communities are small and players get a lot of attention from the DMs (Dungeon Masters). Graphics are outdated as of 2005 - but NWN2 is already in the making...
While there are 'action', 'arena', 'PvP' and other servers, some of them of course have a strong roleplaying focus, and that is where you find the roleplayers amongst the SoLDs.