They could have done that, but with how JASS can be I think SetUnitAnimationByIndex is faster than SetUnitLookAt due to the usage of a string and a heavy amount of variables in the latter. It clearly was more work for them, but if it's faster than all the speed freaks are all over it.
Maybe I should make a model that has its chest at the same point as the origin, and see how much smaller the model size will be. You can then even set the facing instantly. Hey - that seems like it solves all the problems right there. Now I need to study up and find out how to do that.