I mean, I think it's common knowledge that people play fighting games for the fighting. Why would you think otherwise? Most of these games don't even have a big focus on story to begin with. Actually come to think of it, up until fairly recently the "story" in the average fighting game was nothing more than a short bio and a 30 second arcade ending. Just because most of the player base plays offline that doesn't mean they care about the story. I've played through the Weapon Master mode in SCII three or four times and it was for the fun gameplay, not the story. I don't even really remember what it was about other than some guy named Veral looking for the Soul Edge sword and your character has to stop him. Who cares about that? The fun part was doing all the different missions and unlocking all the weapons for each character.