1/ I'm no expert but I think most breeds are a result of years of cross breeding to get a desired result. What is so wrong in that? provided it is done responsibly.
2/ I'm surprised at vets making this comment. A person paying for a dog is willing to make a financial committment and so more likely to want the dog and also to ensure the dog is properly cared for, although I can see there may be exceptions. Why have a go at the owner for valuing their dog? Unless they are stereotyping cockapoo owners, which I think some people do.
3/ I have a cockapoo because I wanted a dog and this breed appealed to me more than others. I wanted a dog with a good temperament, I happen to like fluffy dogs, I wanted a medium sized dog and I have to say like the idea of a non-shedding dog. I did not have one to impress other people. Yet many people I meet say how much they like this breed and want to stroke him etc. and say they would like one.
I love cockapoos