I understand this gets into the area of prejudice and exclusion, but at the same time, form, line and shape in choreography are meaning. Dancers who cannot sustain a line because of their proportions don't have the same impact in adagio - dancers who can't move quickly because of extended limbs have a similar problem in allegro. Another example from choreography - Aria I in Stravinsky Violin Concerto doesn't look the same on a dancer with "proper" classical proportions - it was built on Karin von Aroldingen, who had a very long back and Balanchine used it in a series of backbends.
Yes, it's wrong to be closed minded and exclusionary but there is also a difference between how Herman Cornejo and Marcelo Gomes look in a role. They don't look the same. It doesn't mean the same thing when they dance. They aren't appropriate for the same parts.
I don't disagree. What I object to is critics taking refuge in "standards" that they don't do enough work to articulate or contextualize. Your brief comment above, Leigh, said reams more than most critics do, including Gray: you gave reasons why a certain dancer's proportions matter without recoursing to uncritical, "timeless" notions of "purity" or "perfection."