Yeah, but you're using the prequels as a comparison, which everyone already thinks are bad.
The prequels are bad not because of their villains, but the overall story and the way it was shown.
My comparison is to show that the closer you are to the Skywalker family the more you get fleshed out: and if you're a villain force user it's the only way you're worthwhile in the films. The villains that weren't were rather inconsequential. Kylo had always been more important than Snoke. Episodes 1 and 2 didn't have a Skywalker villain. 3 was when it got real and Anakin got to doing the really bad shit
8 is when the sequels get real. Kylo killing Snoke in that way showed how inferior Snoke was. It also felt like some Games of Thrones stuff to me. Snoke could have had more back story, but does it really matter when he doesn't? Everyone wanted a story to know why they should care about Snoke when he was no longer anything to care about
The prequels were in part bad because of the villains. Almost every villain had no motivation or reason for what they were doing, and existed to be an evil force for the protagonists to fight. Heck, the decisions and actions of the villains (as well as various other characters) were often completely nonsensical. None of the villains seem to have a reason for being evil or benefits from anything they are doing except Palpatine, who's own actions are a round about series of decisions which contradict his own goals and rely on an exact series of events to occur to have any chance of success.
You say "Kylo had always been more important than Snoke" as if Kylo has been in more than 2 movies, Both Kylo and Snoke have only been in 2 movies but Kylo got more screen time.
So yes, Kylo has been more important, but Snoke could have been made more important, or at least given more explanation.
You have to know enough about who a character is and why they are doing something to really care about them dying. What do we know about Snoke? He's a random extremely powerful Sith who showed up out of nowhere, created the First Order without an explanation of how, and dresses like Goldmember from Austin Powers.
So Snoke dies unceremoniously leaving tons of questions unanswered, and the movie just tells you to movie on, we're not going to explain anything to you, Kylo is the new Emperor now, and everyone in the movie just accepts it and moves on like that's normal. ---
The only fool bigger than the person who knows it all is the person who argues with him. They're all complacent sheeple. Passion fights, but reason wins.