I don’t know, as a person who enjoys man different genres of games, I’d have to say that fps’s do take a certain degree of intelligence and at some points even more than that required for an rpg. You need to learn to coordinate and think alongside your team mates in a halo match or cooperative mode as much as you would a raid group. That, coupled with having honed reflexes, and a mind that can think on the fly create a gaming experience that requires thought as well as skill.
Sometimes, mmo’s just feel like I’m typing in continuous patterns over and over again. Use this spell rotation, watch this green or red bar, move two inches to the left every thirty seconds when the boss starts glowing. It all feels very mechanical and hardly as elegant as the thrilling acts of swords and sorcery we all envision in our minds.