I don't get this idea that a line or two from or on Snoke would be a good idea. There are only a couple times when this would even really be possible.
First is from Snoke himself when Rey is brought before him. This would be a terrible idea though. Snoke going on some Bond villain rant explaining where he came from and why would be awful. It would be him saying it to us, the audience, not to Rey. At that point in time when Rey is before Snoke and surrounded by Kylo Ren and the Guards I doubt she gives a crap about Snokes origins or the history of the First Order, she just wants to not get killed at that point.
The other chance would be from Luke when he is giving the story of how Kylo turned evil. This would maybe be possible but still doesn't quite work. FIrst I don't think we want an overlong backstory or exposition. If we are going to get something longer than what we already did get I'd think it would make more sense to concentrate on how Snoke turned Kylo rather than where Snoke came from.
Basically it's bad writing and storytelling to give information to the audience that isn't pertinent to the characters. In this case that character is Rey. There is really no point in this story thus far where Snoke's origin or how he rose to power would matter all that much to Rey. It's just not important to her. Just like if in ROTJ the Emperor would have stopped in the Throne Room scene and been like "now Young Skywalker I will explain to you how I tricked the Senate into giving me emergency powers!!".
There is just no point in this story where Snoke's backstory is relevant to the story being told. You guys want the information just to have the information, not because it matters or is relevant to this story. The movies are not encyclopedias that just give us all the information on every character or event.