I can't agree that all we want is sex. Speaking for myself at least, with the right girl, I want sex and more.All we want is sex - the "long haul" is just so that we can have sex for a long time without having to expend the energy to go look for it again.
there - the secret is out
I don't think sex is always especially meaningful. I've had (somehow) some really fun sex that was just for the sake of sex. There wasn't a great deal of emotional bonding involved. There definitely wasn't a serious connection or deep caring on either part.
At the end of the day, though, I wouldn't have much fun curled up on the couch watching bad movies with an El Camino.