Sigh, meshes, meshes, meshes, and possible bugs.
The engine has two meshes for all human and ghouls, male and female these are the base rag dolls.
When you put armour on it over writes this base doll with the armour mesh changing height, bulk, detail and texture with minimal chance of bugs and even then with only two mesh types - Male and female.
To make fat people, thin people, tall, short, diseased, buff, beautiful and toned bodies would require a total of 18 for a base human / ghoul character and 18 for every unique peice of clothing.
Even if the engine could handle it, and the time was spent to update and implement it the bugs brought up and memory required for it would possibly be overwhelming for such a small pedantic thing to warrant it.
Yes it's something everyone would like to see, but I doubt you will for a long time, and not on this engine.
Yes Gabriel but in FO 1 and two most did not wear armour, they stuck to basic meshes to represent what they were meant to look like if real, not what they actually had on them.