Snoke’s origin could have been included as one throwaway line. Which begs the question why does anyone want it, because he was just generic evil guy no.27. He killed someone or did something, who cares.
He turned Han and Leia’s only son to the Dark Side, and through this destroyed Luke’s Jedi academy. He is personally responsible for building a weapon of unfathomable power using unexplained technology, and destroying the entire New Republic.
He is the most personally and inexplicably calamitous force in the lives of the OT characters in The Force Awakens.
Making him into generic evil guy no.27 means that everything our heroes have ever fought for was undone by generic evil guy no.27.
I’m not even that annoyed by it, but I can see how some people would be.