"a lot of folks still lament KII, insisting that the "real reason" for the change was to use less silver."
IMO "the real reason" (in reality, there were likely several) was the changeover to tempered gelatin emulsions, which allowed for higher temp processing, shorter times (faster throughput), and rougher handling. (The tempered color films I've handled wet -- E6 & C41 -- were tougher than "normal" B&W films, whereas the older (i.e., E4) stuff was so delicate that if you looked at it cockeyed the yellow layer would slip off into the wash (literally!). It was almost impossible to hand-process the stuff without at the very least some nontrivial reticulation.)
You're exactly right. When Kodak decided to create a new, higher temp process (K-14), they had to create new films that could withstand those higher temps (100 degrees F. versus 75 degrees). This allowed for faster developing times, as well as doing away with the prehardener, which was a surprisingly critical step; even the wash time was critical to process control.