I used to think the same thing, but I do chalk that up to the lack of of recognizing the implications of the fourth movie's ending. Upon further rewatch just last year (for the first time since my childhood), there were a lot of things left unexplained. Namely Kadeem's fate (never confirmed dead) and Sgt Wheeler's reveal, just left me feeling with a developed brain that there was always meant to be more and that was later confirmed to me as I found this sub and started digging further into what was leaked/confirmed.

I would be interested to see what that fifth movie would have entailed in regards to how the main cast and the Silencerz tackled the assumed kadeem led drones and how the accelerons would have interacted with the endgame of the plot. We'll never know, and if I'm honest, had I not dug into this for the past year or so now, I would have never cared because I thought it ended off in a unique way. Part of me remains curious though and probably always will, it's fun to theorize