One thing I'm really fascinated about with Obsidian is that they've made a game in virtually every sub-genre of RPG. KOTOR 2, fairly console party based RPG. Neverwinter Nights 2, PC party based RPG. Alpha Protocol, cinematic RPG in the vein of Mass Effect. New Vegas, open world. Dungeon Siege 3, hack and slash. You've even got fantasy, modern, post-apoc.
I don't know if this was ever their objective, to try out different things and explore around the genre. But I do know that it's been quite a variety of experiences following their games.