I get that it goes against the fundamentals of crypto currency, but exactly for what reasons though? Assuming you're not using it for anything illegal (if you are then it's understandable), why the concern? I'm asking specifically when trading.
I can't speak on behalf of everyone else, but I can say that the clearest thing for me is the fact that we are talking something that is seriously important in privacy for me. Why would I want that data to be shared with anyone? Like what could be the reason to "want" something like that?
If we do not want it, then the feeling drops to "being okay with it", like it is not something I want, but if I am forced to do that to continue then I would be okay with it. Suddenly it becomes a lot more logical to understand why people do not want to share it, they do not like it because it is not something they want to do anyway, so it is forced on them.
Secondly and more importantly, I do not trust them to keep it safe, I have seen too many places that got hacked and all that information shared with others, that is enough reason to not want it because bad people could get their hands on it.