If one of Microsoft's video codecs like VC-1 offered even better power efficiency and technical superiority, and "looked better" than h264 (whatever THAT means), would you still be a fan of using the "best available" proprietary codec? Would you be in favor of Google and other companies paying Microsoft license fees to use the codec? Or would you be arguing for the use of the "inferior" h264?
If it was already shipping on 97% of computers and had widespread hardware acceleration support in mobile devices, sure why not? I have no allegiance to h264.
VC-1 has hardware support in a number of areas and is included in WMP since at least 10, IIRC. h.264 still is not supported on any version of Windows before 7, and is only available in Flash.
Supporting h.264, with your logic, makes no sense.