Why doesn't Data ever just accept who he is? What exactly is wrong with being an android that has capabilities to learn, understand and (as McBain pointed out) have enough emotions to have relationships with the crew? Why is being an android so bad? Sure, there's a want to have more, but he would willingly give up everything to be human. Being human and wanting to become a member of the human race are not mutually exclusive if there are aliens who share the same needs and wants.
This feels less like Data seeking enlightenment and more like Gene's pandering that the human race is so freaking awesome that everyone and everything should want to be us even at the expense of what makes themselves unique and different.