The below video is of the Dallas Love Field Airport OIS.
Fast forward to about 2:35
What does this video show? Pistol calibers are ineffective against human adversaries. It does not matter what caliber you carry, it does not matter how many times you shoot someone, it all comes down to accuracy. A .22lr round fired directly into a switch will cause more damage and response instantly than several .44mag rounds fired into timers. The officer discharged his duty weapon center mass and the male went down, this may be a sympathetic response to being shot (as most people will default to falling down when they don't actually have to) and then after realizing he was not dead he got up and continued his deadly force-level assault. It is also unclear if this person had any chemicals (narcotics) in his system which would aid him in not feeling the pain right away.
Accurate shots are what stop deadly threats, continuously shooting a person with pistol caliber without actually hitting anything vital is not going to win any fights quickly. Consider a mutual gunfight, where the bad guy has a weapon like a pistol and there is an exchange of fire. Even if the bad guy is shot several times he would still be able to shoot back.
The argument for rifle caliber is always strong and while most US LEO's carry pistols and discharge pistols in very high numbers more than rifles, the facts do not lie, pistol calibers do not do the job as effectively and as fast.