"My character is ready. What? Oh, I need to get some flaws to pay off all the extra stuff I've already picked. But my character is perfect... Now, what flaws would have least effect on my character?"
Sounds familiar? All too familiar to me. Most of my players want to think of all those munchkiny statistics and features first, and then, if the system has a mechanism for negative features (flaws, hindrances, disadvantages, whatever they are called), they try to find something that doesn't hinder their character. I confess, I'm guilty of that too.