Which wouldn’t work for this game. You buy and sell clothes. It is an rpg so your character constantly changes clothes.
So the body and the clothes must be seperate meshes. You can’t simply connect it to the body mesh. It must be created seperate from the body. Otherwise, thousands upon thousands of meshes would have to be created in order to keep up with every single clothing combination in the game. Considering that it takes place over pretty much an entire continent and two islands… it would be EXTREMELY hard to do it that way. 
Each clothing item must be it’s own mesh and rigged. Then you just tell the game that is a clothing item and what body part to attatch to and place it wherever you want in the game and it can be worn by any character you so choose. 
So yes, I have to rig it for in-game use, otherwise it won’t flow with the skin. You can’t simply delete parts of the mesh underneath and weld it onto the body.