I've yet to see a metric that encapsulates rushing efficiency/success into a QB's worth...and that's increasingly antiquated for today's NFL.
Running in general has always been a potent addition to any QB's game. Aaron Rodgers, Roger Staubach, Russell Wilson all have used it very effectively.
But unusually high QB rushing TD totals tell me either the offensive scheme, the skill players, or the QB have weaknesses otherwise executing.
Cam Newton represents this extreme. I don't care if you're built like Superman, I need you to be healthy on the next drive. You have RBs and WRs paid to protect the football and outleap defenders. Throw the damned thing!
Especially in the redzone! I absolutely don't want my QB rushing into a thick of defenders if I can avoid it.
1) A QBs health is critical to their team's success and defenders can unload on QBs who run.
2) QBs don't practice ball safety like backs do, and they are usually fumble-machines.
So IMO QB rushing TDs should be rare, 3-4 times a year max and almost always when I can fake defenders into no contact.
Dak ran for too many his first few years, IMO, and 2019 was just about perfect at 3.