Fans should probably count themselves lucky to have gotten one more season at all, even if it is shortened!
Plenty of time for more gnarly serial killers, right?
Additionally, rumor had it back in October 2018 that CBS has limited interest in continuing Criminal Minds due to the fact that ABC is actually the lead studio; throw in the disappointing ratings, and CBS may not have felt justified in putting up the resources for the show to continue indefinitely.