Snoke should be Plageus! Snoke as just Snoke is boring and wreaks of being a plot device to keep the cash cow, that is Star Wars, from drying up. Having just another evil figure head, who emulates the dead Emperor Palpatine in what is a carbon copy of the Empire will eventually wind up as a poor cousin. Oh sure Episode 7 was fun but its ham-fisted allusions to the original trilogy and thin allusions to future development probably won't hold the audience for long in Episode 8. So how to add gravitas to this new series? Exploring the one mystery the prequels created may just be the ticket. (What! The prequels!...No I'm not talking about Darth Jar Jar...ha ha ha.)
"Sith" did not become a household name before the prequels and no one knew that the Emperor also went by the "Sith" title of "Darth" By developing the Palpatine character and exposing light on his machinations also allowed audiences to notice the deepening void of knowledge about the Sith. (Sure there's the expanded universe but all those stories are non-canon and unknown to the majority of the movie audience.)
The greatest of those mysteries were Darth Plageus who Palpatine referenced in tempting Anakin to the dark side. Palpatine's downfall in ROTJ was his arrogance. Could that same arrogance have fooled Palpatine into believing he had successfully murdered his old master? Or maybe Palpatine was not eluding to himself when he said Plageus was killed by his apprentice. Maybe Palpatine was actually telling "an old Sith legend." In any event exposing Snook as this ancient Sith lord would elevate the new series and help further tie all past and future films together by creating a larger story arc that encompasses the Skywalker family saga.
Worth mentioning is the excellent Darth Plageus novel now branded as expanded universe. The story may not be canon however this book is referenced in the General Tarkin book written by the same author that is considered canon. So there is a lot of really well developed material for the filmmakers to considered if Snook is indeed Plageus.
(By the way, anyone else feel silly when using the word canon when dealing with sci-fi fantasy stories?)