Keith Laudenberger We hear you. No one here thought it was a "good idea" to not have BToE working on 3PIP phones with Teams. It was simply not possible to do; 3PIP phones don't run our SW, they run OEM SW which does protocol interop with Skype for Business. OEMs implemented BToE themselves, in inconsistent/ different ways.
The above is exactly why everyone should care about actually having native Teams apps on phones; because we write the SW which runs on the phones and we can enhance that SW quickly. You will see BToE / "better together" scenarios coming to Teams Phones "soon" (come see us at Ignite!).
We did the best we could with getting 3PIP phones to work on truly basic functionality when a user moves to Teams, and that was a significant set of work. However BToE was not "basic functionality" and we just didn't have the ability to make that work with Teams without having a true Teams phone.