Indeed,
there are also a lot of headswaps ported to the game wich retain the whole textures of both original models (basically all the models where you find 2 texture folders), that was bad editing by the original creator and lazy porting by the dev, but he's clearly workin' on quantity, not quality.
An already good model should be around 15/20 Mb tops.
Unfortunatly I don't see it getting any better with the new wave of super hi-poly ports from blender wich will eventually end up in here.
Man... yesterday I downloaded a model 170 Mb compressed! open it.. and it looked shittier than a basic Miku, WTF!

(small detour, sorry)