No, not at all. A relationship is more than just sex, I don't care how good or bad it is. And I'm getting ready to go all old-timey after-school psa here: when you truly care about someone, that makes the sex all that much better, too.
Good sex is great but eventually that'll die down (hard to believe, I know) and you'll want companionship. And that'll be pretty hard to get with someone you have zero connection with.