Specifically, I’m thinking about the use case of a 2.79 user migrating to 2.8. If they have a custom keymap (which is likely), there’s a good possibility they have tons of deprecated operators bound to hotkeys and have no idea.
Currently, the first warning sign a user will get will simply be that their hotkey doesn’t work. Digging deeper into the input manager, they’ll see the telltale signs of an invalid operator. From here, we’re leaving them hanging- they don’t know if this operator has just been simply renamed or had their usage tweaked (as in the case of collection.create vs group.create) or completely removed. A majority of users do not keep up with development and won’t have the tribal knowledge necessary to perform a productive google search, so ultimately we’ll just end up with a bunch of threads on blenderartists.org asking how to fix things.
Ideally, it’d be great to see migration written for these sorts of things- but at a minimum it could be as simple as keeping a list of deprecated/changed operators posted on the wiki, and then print a deprecation warning to the console with a URL when one of the old operators is called. An official list of changed operators would also be extremely helpful for addon developers that want to port their scripts to 2.8 and utilize built-in operators.