Are they that bulky though? Or for that matter, are the Dracthyr that slim?
Seems ot me like they took a generic fantasy dragon and made it look convincingly like a creature of that size. Whereas the Dracthyr are designed as humanoid dragons with an androgynous appearance. Making it slimmer seems more to me like a natural progression of making it less masculine, which is a problem that the "fixed" version of the Dracthyr above have.
Sure it looks more menacing, but the broad shoulders and prnounced chin makes it immediately apparent to human pattern recognition that this looks like a male, which is an issue the other one doesnt have.
Regardless, sliders are going to be a thing, so probably won't matter that much in the grand scheme.