William Shatner thought Star Trek: The Next Generation was initially a mistake

The entire idea of Star Trek: The Next Generation wasn't welcomed by the diehard Star Trek: The Original Series fans. They weren't interested in a show that didn't have Captain Kirk (William Shatner), Spock (Leonard Nimoy), and Dr. McCoy (DeForest Kelley). In fact, many swore they would never watch it. But they weren't the only ones thinking the series was a mistake.

According to an interview William Shatner gave in Starlog Magazine in 1987 [via Fandomwire], he wasn't enthused by the project, either. In fact, he thought there was the possibility of The Next Generation not having the quality that fans were used to.

"I think it is a mistake. To call a series Star Trek that doesn’t have the cast and the ship in it is an error. The error seems to me to be overexposure of the Star Trek name and the possibility of not having the Star Trek quality we’ve become accustomed to. It remains to be seen."

- William Shatner

In all fairness, this is an actor who was (and remains) a big part of Star Trek, especially the beginning. The Original Series movies were successful at the time, and fans would have undoubtedly preferred a newer version of The Original Series rather than a series starting from scratch. The only thing familiar about The Next Generation was the Enterprise, and though the ship is a character in an of itself, most everyone felt that the ship needed the other characters to make the show succesful.

You can't fault someone for believing the powers-that-be were making a mistake. Even several of The Next Generation actors themselves didn't believe the show would last very long so Shatner was just saying what the fans were saying. The only difference is they didn't have a public platform like Shatner did.