It's about shape first and foremost. If the shape is alright then bigger is better. A good boobjob can make really great tits out of small or unshapely ones. It's silly to be categorically against cosmetic surgery. if it's done right it can make a beautiful improvement.
If the choice is between beautiful fake boobs and ugly natural ones I will always go with fake. If it's between beautiful small boobs and beautiful bigger fake boobs I'll take the latter.
There are as many ugly natural boobs as there are ugly fake boobs so this is clearly a case by case situation.
If the woman wants this to feel more attractive I don't see anything wrong with it. It's the same as:
makeup
hair coloring/extensions
tattoos
jewelry
sexy clothing
a trim body formed by exercise
etc.
Drawing a line at surgery is too arbitrary for me.
If you demand respect or gratitude for your volunteer work, you're doing volunteering wrong.
