Your logic is flawed in the fact that a lot of the modifications you've brought up are only popular because people are striving to achieve desirable traits which, generally speaking, only a minority of others have naturally. As
@espressoenthusiast so eloquently stated, 'what is valuable, is what is rare, not what is bought'. Sure, you can modify yourself to attain certain standards of beauty, and I by no means condemn that, I'm all in favour of doing what you wish with your body to make yourself happy, however, it's silly to think that a bought beauty will be regarded with the same admiration as a natural beauty, which is precisely why these celebrities are never completely candid and open about the work they've had done, they know it degrades the value and rarity of their looks.
With regard to models, fashion is aspirational and fantastical, I would far rather see a girl and think 'wow, what ethereal beauty, what stunning bone structure, what an incredible combination of genes' than 'wow, what ethereal beauty, someone has clearly spent a lot of money to pay someone to create that face and I could just as easily do the same'.