It costs so much more to design for fatties. When you design a range of normal sizes you just start with a human body shape and scale up. Once you have to consider planets and their weird distribution of adipose it results in a completely different design. And it still won't fit the majority properly as they all look so different, some have enormous gunts, others have those legs/feet that spill out of their shoes, FFS some even grow lard on their fucking foreheads.