The reason they had to reboot it all with the timeline reset in the first film is because of some strong limits on what Paramount (the movie studio) is allowed to use. Paramount (the movie studio) and CBS (the TV network) used to be part of the same company but then they split. And part of that split involved some deals that granted Paramount the right to produce Star Trek feature films but limited what parts of the Star Trek universe Paramount could use in their films. CBS kept the right to use the entire Star Trek universe alongside the right to produce Star Trek TV shows.