Thank you for taking the time to write this.
One of your example shows the weakness of the HOI3 system. Why does a completely nonsense unit like LARM/INF/AA/RART get +30%(40-45 with proper commanders) magical combat efficiency?
It may be magical, but it also does not make that division actually any good. If a player is just chasing CA bonuses, they will build crappy divisions.
As I point out in the strategy guide for HOI3, divisions have to be built with several considerations in mind, including mission, terrain penalties, firepower type, speed, and a list of other things. The CA bonus, like SA, HA, and suppression, is something that should be considered, but not necessarily be the end goal of optimization.
The reworking of the CA bonus for TFH was an attempt to fix some of the ridiculous division compositions of previous versions of the game. Say what you want about HOI3, but it had a nice library of brigades to use in divisions. Too bad that most of them were next to worthless prior to TFH. In TFH, they redid unit stats (AC woo hoo!), but they also changed how the CA bonus worked to encourage more diversity in units. It kind of worked. Instead of all armored divisions either being pure armor or just ARM/SPART spam (or even worse, MECH/TD spam), you started seeing various division types. LARM/MOT/AC/AC, or ARM/MOT/TD/TD or ARM/MECH/SPART/SPART or even ARM/MECH/SPART/SPAAT (for countries with weak air). The CA bonus being spread around helped convince players to use diverse units.
But...
The CA bonus also ties in with the leader stuff and doctrines. By reworking the CA bonus to exclude MIL, it prevented stupid cheesy strategies. By requiring some kind of infantry, armored divisions started seeing MOT and MECH far more often. Coupled with the armor-penetration mechanics, there was no more need for stupid 4xHARM divisions; HARM/MECH/whatever would be far more efficient all around. Then you have leaders that either start with battlemaster or who gain it from leading CA divisions, you end up with a better system of grooming leaders.
I feel the CA system in TFH, coupled with other changes, made division composition much more realistic.
Now, maybe HOI4 will be able to work without the CA bonus in any form. But I keep wondering what will happen with this new battalion system without any CA bonus at all. Will we devolve back to unrealistic pure ARM divisions from earlier HOI3 instead of better INF/ARM configurations?