So Canon doesn't provide a proper way for other manufacturers to make EF lenses without paying horrendous licensing fees. Then it purpously breaks compatibility with existing 3rd party lenses with new bodies. That doesn't sound good to me. All Canon would have to provide would be a proper way to ID the lenses. A simple manufacturer ID + item ID would be sufficient.
Third party manufacturers can assign their own lens ID, they do not need to use a Canon ID. They are merely trying to be clever, and it backfired.
However, the only way for a camera to know the optical and capable characteristics of a lens, is for the lens to be in the internal table that resides in the camera. So, Canon would have to maintain data for all the competitors lenses and issue camera firmware updates for them, and get complaints when problems occurred.
Thats like saying car makers should design cars to work with all transmissions from other makes. Then, whenever they want to make a change or improvement, they must get everyone else to change.
Its not so simple as one might believe.
But, the lens correction feature is not mandantory, if a user wants to use a third party lens, he can turn it off. Canon has actually provided for third pasrty manufacturers, you merely cannot use the lens correction feature in camera.