I think the issue here is more about the operating temperature of the semi-conductors. It's only recently that chips running at 400 C (?) using silicon carbide

I think the issue here is more about the operating temperature of the semi-conductors. It's only recently that chips running at 400 C (?) using silicon carbide or Gallium Nitride semi-conductors has been practical and cheap enough. So these electronics can be integrated right into the motor without extensive cooling. This same technology is having an even more dramatic impact on High Voltage Direct Current (HVDC) transmission lines where costs have been dropping very quickly.