Agree 100%! ... There is no telling if the green speed numbers in WGT are very close to those on the real golf courses. The fact that they correlate means very little unless that correlation coefficient is approximately 1.
Besides, if WGT was a true simulator we would not see players shooting regularly in the mid 50s or even below 50s.
I think that says it all; i.e., like you suggested: "this is a computer game !" And that is all it is. Nothing more, nothing less.