“He also wore black. Do you want Kylo to wear something else just to emphasize the unnecessary points of originality?”
Originality/subversion alone doesn’t do anything. However, if we’re dealing with a good film that features competent writing, direction and acting, would you think its quality be hurt if you saw the villain wearing white robes and using a blue lightsaber?
Yes however little. It would be a unnecesarily misleading and confusing design choice. Why make the bad guy look so much like the good guys? It’s not even really that original and detracts from the story.
EDIT : Starkiller Base does serve a purpose. It makes the First Order a humongous threat and gives Poe Dameron something to do in the third act.