Section 31 introduced a new character to head up Starfleet's grey area Intelligence Division, and, in doing so, added an extra level of confusion. It was just one more character that had to be created along with the others from a group of misfits we fans had never seen before. However, had Shazid Latif been cast in the movie as Ash Tyler, it would have made a lot more sense. Trekculture even asked where Ash Tyler was when the cast of the movie was introduced.
Tyler had already been a part of Section 31. Philippa Georgiou [Michelle Yeoh] would have instantly recognized him. No, they weren't fans of one another, but that had worked together. Adding another familiar face would have increased the probablity that fans would have been more open to the plot of the story. On top of that, Ash was, for the most part, a well-liked character, once we got over the fact that he was a genetically modified Klingon.
Star Trek: Discovery delved more into Section 31 and had the movie used what was introduced in the series a bit more, we might not have as many fan complaints as we do right now. Sometimes, the old works just as good as the new, and having Ash and Georgiou to play off one another would have added another level of grit and humor.
Section 31 ended with the new team getting another mission from guest star Jamie Lee Curtis' character. If Paramount does decide to take a chance on another movie, which will be surprising considering the backlash of this one, the executives would be wise to use what works. And incorporating a welcome familiar face into the film would help smooth out the very, very rough edges that this first Star Trek Paramount+ streaming movie had.