10. Brave New World
By 2001, the first stages of franchise fatigue were starting to set in. Deep Space Nine had concluded in 1999, Star Trek Voyager had just wrapped up and Insurrection had underperformed at the box office. Along came this new show, going back to basics by revisiting a time set before the establishment of the Federation.
The first issue it got caught up with was canon. In the pilot episode, a bumpy headed Klingon was seen running through a cornfield on Earth. Barely three episodes later, the K'Tinga Class battlecruiser was flying through space. To canon purists, both of these were examples of committing huge sins. EVERYONE knows that the Klingons had smooth heads until the movies. EVERYONE knows that the K'Tinga class was only introduced in the Motion Picture. Seemingly just dropped in, these only served to fuel the fears of old fans.
Add to this was the simply idea of exploring strange new worlds. If Discovery and Picard have done something right, its addressing the fact that much of the Star Trek Universe already has been explored. That is not to say that they should not seek out new life and new civilizations but, in 2001, people just weren't into that.
The tone also jarred horribly with real life events. 9/11 changed the world and TV started to adapt. The revived Battlestar Galactica took this head on, while Enterprise looked like it was ignoring it. Whether that was an unforgiveable crime is for history to decide but the show is certainly far more palatable in today's climate.