Based on what I read in Wikipedia, I think the idea of "an elogated pilot" extended into movie length seems plausible.
Star Trek: The Motion Picture
From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Star_Trek ... on_PictureWhen the original television series was cancelled in 1969, Star Trek creator Gene Roddenberry lobbied Paramount Pictures to continue the franchise through a feature film. The success of the series in syndication convinced the studio to begin work on the film beginning in 1975. A series of writers attempted to craft a "suitably epic" script, but the attempts did not satisfy Paramount, so the studio scrapped the project in 1977. Paramount instead planned on returning the franchise to its roots, with a new television series titled Star Trek: Phase II. The box office success of Close Encounters of the Third Kind, however, convinced Paramount that science fiction films other than Star Wars could do well at the box office, so the studio cancelled production of Phase II and resumed its attempts at making a Star Trek film. In 1978, Paramount assembled the largest press conference held at the studio since the 1950s, to announce that two-time Academy Award–winning director Robert Wise would direct a $15 million budget film adaptation of the original television series. With the cancellation of Phase II, writers rushed to adapt its planned pilot episode, "In Thy Image", into a film script. Constant revisions to the story and the shooting script continued to the extent of hourly script updates on shooting dates. The Enterprise was modified inside and out; costume designer Robert Fletcher provided new uniforms, and production designer Harold Michelson fabricated new sets. Jerry Goldsmith composed the film's score, beginning an association with Star Trek that would continue until 2002. When the original contractors for the optical effects proved unable to complete their tasks in time, effects supervisor Douglas Trumbull was given carte blanche to meet the film's December 1979 release date. The film came together only days before the premiere; Wise took the just-completed film to its Washington, D.C., opening, but always felt that the final theatrical version was a rough cut of the film that he had wanted to make.
Released in North America on December 7, 1979, Star Trek: The Motion Picture received mixed reviews from critics, many of whom faulted the film for its lack of action scenes and over-reliance on special effects. Its final production cost ballooned to approximately $46 million, and earned $139 million at the worldwide box office, falling short of studio expectations, but enough for Paramount to propose a cheaper costing sequel. Roddenberry was forced out of creative control for production of the film's 1982 sequel, Star Trek II: The Wrath of Khan. In 2001, Wise oversaw a director's cut for a special DVD release of the film, with remastered audio, tightened and added scenes, and new computer-generated effects.
The script was a pilot for a reboot of the series. They had to add a ton of filler to get it to movie length and it's all that filler that tends to make the movie disappointing (unless you happen to like to see lots of minutes of a remodeled model enterprise).
