First I think it’s important to define what I mean by villains. To me there’s four types of the “bad guy”.
You have your Anti-hero. They’re aren’t too good and sometimes don’t have good intentions but they do the right thing in the end. Characters that have redemption Arcs usually fit this group.
Next are Anti-Villains. They are opposites to Anti-heroes. They are good and usually have good intentions but they end up doing the wrong things. They have tragic past and tend to be misled or manipulated by someone else. they also fit the redemption Arc group.
Then are your Antagonist. They aren’t necessarily good or bad they just oppose the main character. Antags can be good or bad depending on who the protag is.
Lastly you have villains. People that are evil for the sake of being evil. No real rhyme or reason to it.
Based on what I’ve been reading and watching, Villains are on the decline or at least as the main “Bad guy”. And I understand why. AHs, AVs and Antags tend to be more compelling. They have more layers to their Character Arc and development. Readers and or watchers want great characters. Writers have more options and ways to make a bad guy a rounded character if they’re an AH, AV and or Antag.
Just because a villain is Pure Evil doesn’t mean they can’t have layers. Pure Evil doesn’t mean Static and Flat. Villain can also be great characters. What was the point of no return for them? What are lines they won’t cross? Are there rules to their evil? Give them a Failed redemption/ Betrayal Arcs. They’re still evil but you see into their character more. You probably won’t sympathize with them but at least they are more than they guy trying to blow up the pretty girl ever chapter/episode.
Villains are great and they should Continue to be written. They don’t have to be Flat. It’s possible for Villains to be well rounded it just takes a different writing approach.