>Why not instead of "change" just make a new interface and give users the option to switch if they want. This approach seems too rare.
Because it duplicates options, separates the users in two camps, adds 2 (or more if you keep doing it) interfaces for the dev team to keep supporting, and so on...
Give users the option to keep using the "familiar" interface, but without any "support". I suspect many user actually require "support" because of interface changes.
IME, observing other users, it is the forced change that is offensive to some. They do not complain about "lack of support" (many want to be self-suficient and do not want to keep asking for "support"), they complain about changes that they see as unnecessary and that will just require more effort to learn.
Because it duplicates options, separates the users in two camps, adds 2 (or more if you keep doing it) interfaces for the dev team to keep supporting, and so on...