When Star Trek’s Original Series first aired in the 1960s, one theme was a constant – the theme of looking to the future. Roddenberry’s utopian vision of the future centred itself around the philosophy of working to better oneself and the rest of humanity, about looking ahead to the future, rather than languishing in the mistakes of the past. Of course, it wasn’t about forgetting those mistakes – it was about learning from them, and moving onwards.
This theme was carried right through The Next Generation (TNG) era shows and films. They all looked to the future; to the continuing evolution and betterment of humanity.
Things changed upon the release of Star Trek: Enterprise in 2001, which began a trend of producers and writers choosing to focus on a period of time before The Original Series (TOS). Enterprise and the currently airing Discovery are both set in the Prime timeline, before the events of TOS, while the J.J. Abrams produced films are all set parallel to the Original Series, but in the entirely new Kelvin timeline. The chance of a series or film that is set in the post-TNG time period being produced is beginning to look very slim indeed.
Source: IGN.com How Star Trek Online Continues the Legacy of Classic Trek