In order to make the try out for RE4 and get the spot, she needed to have bigger and sexier boobs. While her father disagreed with the ordeal, she was too star-crazy and saw her big chance for fame in life. She spent her entire college fund on the boob job in order to get the position in the game.
And the secret deep meaning behind all of this is that she just wanted to have a chance to get closer to Leon and swoop him up to be her lover. It's a real pity he turned her down after all she went through.
After what she did, her father disowned her and she's probably smoking crack on the side of the street and whoring herself out to men, because she has nothing left in life.
The only reason her father wanted her back so badly in RE4 was because he wanted to give her a strong and well-deserved pimp slap across the face, before sending her off to live a miserable and hollow life on the streets.
I believe we have learned a valuable lesson from all of this.
