Star Trek has now turned into good guys vs. bad guys since Star Trek 2. If you watch the series, Star Trek didn't have many villains
Not sure that's entirely true. TOS was full of nefarious sorts up to no good: Dr. Tristan Adams, Roger Korby, Trelane, the Gorn, Khan, Kor, Sylvia in "Catspaw," Redjak (you don't get more villainous than Jack the Ripper!), Mudd, Koloth, the evil Romans in "Bread and Circuses," the assassin in "Journey to Babel," various bad guys in "Private Little War," the evil brains on Triskelion, Sargon and company, Nazis, Captain Ronald Tracy, Gorgon the friendly angel, the sadistic Platonians, "Lord Garth," Dr. Sevrin, Colonel Green, Janice Lester . . . .
And that's not even counting all the misguided, desperate aliens that threatened Kirk and crew in "A Taste of Armageddon," "Wink of an Eye," "Mark of Gideon," "The Cloud Minders," etc. And all the homicidal computers with delusions of grandeur.
Rarely did an episode go by that somebody wasn't capturing the landing party, threatening the Enterprise, and probably killing a few redshirts . . . .
Good times.