Yes there will be a day of “forcing”. One day the MacOS version will move to the “new” version of Outlook and the “revert to legacy” function will be gone. There are no registry hacks in MacOS to stop that.
The day will also come that native Outlook app support will be stopped. Not because the client will no longer posses the capability, technically. But because Microsoft will end support.
At that time you’ll move over or not have email. It’s not the first time this has happened, by the way. But the way that you claim there isn’t any “forcing”, is strange. Of course they can’t literally make you use their new ****. You just can’t use the native app version you like. They will freeze you out. So it’s webmail for you, or what?
I have a solution for my personal space. I’m a Mac user. Apple mail will work. It won’t have all of the feature set, but it’s native and it’s an actual email client.
In the professional space, I’m screwed and forced to use this “new” garbage.