There's nothing wrong wanting a slim and small 'character' - I imagine folks are looking for a more 'cute' version of 'Bosmer' - Elder Scrolls; wood elves that are petite and lean and spend their times up in the woods/trees and have a somewhat similar lifestyle to Viera. However; that race does not look like children even if they're small and petite - which is acceptable to me. While they are certainly youthful and can be made to look 'young' adultlike they look mature enough to not be questionable. And of course the females look similar to the males - they are both small.
What I'm getting from here is that folks want male Viera to look beautiful/small and thin - but beauty is in the eyes of the beholder. Some folks do not want to play as a race that objectively looks like a pubescent. Examples such as Seiryuu and Omega M are fine to make, they - to me do not look like young boys due to their body proportions; they are certainly not 'small' however.
If we go even more in-depth and to step away from examples that may have moral issues attached;

It seems that individuals want 'Short and Thin' - while the lore, and what others seem to want is a mix between Average Height and Weight, Average Weight and Tall or Tall and Thin (If going off the females bodytype.).
To confirm; those who want a small petite Viera, is 'Short and Thin' the visual you're going for?