Disagree. Sex is one of our most basic animal instincts (never mind the fact that most species on earth need a male and female subject to reproduce). I don't think that sexual gratification has any real connection with self-esteem issues, or an unfulfilling life. It's a pleasurable stimulus and people seek it for just that reason.
Psychoanalyzing virtually everything that human beings do is a part of the problem. I think we read too much into things and try to explain why humans do things when in reality, there may well be no underlying, subconscious reason, apart from nature enforcing it’s laws on us.
Personally, so far I’ve had a very satisfying life and I feel very accomplished. Lack of confidence is not something I suffer from, as I’m very in-touch with myself. Yet, I used to hook up every now and again with people that I didn’t know that well. They weren’t strangers, but we had no other connection apart from physical attraction. I think it has far more to do with being able to separate sex and emotion, and not lack of self-esteem.