Whereas its predecessor struggled for life each season, Star Trek: The Next Generation increased in popularity each year. It was a groundbreaking, landmark series beloved by millions with a cast of actors who, to this day, adore each other. Yet, the first two seasons of Star Trek: The Next Generation were a struggle, on- and off-screen. If not for the iron-clad commitment Paramount had to the series, it may not have even lasted as long as The Original Series. Announced as part of Paramount's Star Trek 20th anniversary celebration, The Next Generation was not a sure thing. No sequel series ever outperformed its predecessor. There weren't many examples, but a handful tried, including Paramount's own Mission: Impossible.
Source：https://www.cbr.com/why-star-trek-tng-struggled-first-two-seasons/
