I mean the story portion to the game and the narrative in general make a significant portion of the game, not just the romances. If it didn't have the draw of Bioware storytelling it wouldn't be nearly as popular. While I can't speak for everyone I can say that I wouldn't have even considered the game if it weren't a KotOR sequel developed by Bioware. The fact that it was an MMO kept me out of the game for a while, but eventually I did play and enjoy.
Story was often referred to as the "fourth pillar" of ToR and its existence was designed to help set this MMO apart from others.