I've raised feedback a few times on things missing from the new UI. Some fields don't appear and (as an example) comment visibility can't be changed in the new UI.
So the decision of which to use isn't subjective.
It is possible to either make the traditional UI the default or allow an Administrator to set the default for all / new users?
More generally can Atlassian please offer such changes by opt-in (as it once did) rather than by default?