It's interesting that some people think every member of the race has the exact same body type and height in cannon. It should be obvious that High Elves have several different heights and body types. A new model would just represent a different group. No one thinks that the defias with the skinny model are a new "race". They're just workers from Stormwind. The new model is just a different look. It's a design choice. High Elves can easily have the same thing.