Quote from TNG episode The Offspring
Lal: Then why do you still try to emulate humans? What purpose does it serve except to remind you that you are incomplete?
Data: I have asked myself that many times as I have struggled to be more human, Lal. Until I finally realized that it is the struggle itself that is most important. We must strive to be better than we are. It does not matter that we will never reahc our ultimate goal. The effort yeilds its own rewards.
I always found it kinda ironic that in trying to explain to Lal why he struggles to be more human Data ends up describing what it is to be human, at leats imho. This entire episode makes it very difficult to believe in Data as an emotionless being. Even Dr Crusher within the episode states that she finds it hard to believe that Data is incapable of providing Lal with love.