Unless your kit says you get the chance, you don't get to roll for it. I don't want to see a character get completed and then roll for wild talents and get totally boned by becoming a vegetable. If you get to live with the good, you have to live with the bad.
However, you make a good point: if you want to bone yourself out of your character, that's your choice. But it makes me wonder if you aren't happy with what you've created to begin with?