My observation is the "old Microsoft" would have kept it in and supported it because that's how they rolled. The lack of NTVDM in x64 Windows signaled a change that the commitment to compatibility is now on shaky ground.

Whether it should have been kept for a technical reason is secondary, in my mind, to eroding the confidence their Customers had that old software would continue to work.

The market doesn't seem to give a damn so I guess they made the right call.