I'd rather not have this forced on the playerbase. Typically that doesn't end well, and those that want to roleplay taking their oaths seriously will do so already.
I agree that it shouldn't be forced.
One should be able to choose, oath or no oath, as lord, Duke ruler and knight.
As a Lord, just don't make any oathed estates, as a knight, look for oathless estates, if you cant find them or enough in your realm, join a realm with regions who do.
This will bring people together who do care, but also those who don't.
It makes it easier to find the place we are looking for.