The point is, code "ownership" shouldn't be understood as a term of property - of course it isn't the property of the programmer but the company - but in terms of responsibility.
This might be different in very large teams, but usually, once you write a piece of code, you are the the prime responsible person for maintaining it. And as long as this is the case, I would expect to be involved in any significant change to the code. Of course I am fine with changes, which also transfer the responsibility :)
This. If some developer get offended when there is some issue in their code or the way it got implemented either they are not mature enough or there is a cultural issue in the team.