15 years ago there were people who said exactly the same thing about MPEG4-ASP (eg. divx/xvid). It all comes down to Moore's law and hardware acceleration.
Another thing about hardware acceleration is that on many platforms you really did not want to push 622Mbit/s worth of raw chroma-subsampled YUV FullHD video across whatever interconnect to your GPU, so moving things like motion compensation into GPU hardware was only way to actually play FullHD content. And this is also part of the reasons why is H.264 somehow special today.