DOW2 and COH2

One thing you chaps might know is that DOW2 is on the same engine as CoH. One thing you might not know is how different it is (file-structure, gameplay elements, etc.).

Overall, the game/engine is actually somewhat superior to CoH. There are many new capabilities, and many gameplay elements have been updated (Example: Squad-ai is attrib-based and has more options than CoH), and while some things have been simplified (there are only 5 types of cover compared to CoH's 10), and others might seem to be missing at first (Weapon accuracy system), are actually just in different places (Weapon accuracy has been replaced by damage, per say. All weapons have a accuracy of 1 that can be decreased through cover modifiers. Damage takes the mantle of dealing with distance from accuracy, as damage can now be reduced depending on distance. Armor and penetration is a thing, but its somewhat under-utilized). Formations have been consolidated and are much simpler to use but not lacking any functionality, and Scar has been expanded.

However, all of this stuff is relatively unused. It does make sense, as DOW isn't supposed to be as realistic/tactical as CoH, focusing more on good micro and effective ability usage. What strikes me as odd is that some of the changes/additions that would be a good thing to carry over to CoH2, like the squad-ai and knockdown system (infantry can get knocked down depending on the force of a explosion or during a charge, bigger/better units have less of a chance of being knocked) weren't. In-fact, CoH2's version of the engine seems much more similar to Essence V1 than V2 of DOW2.

Anyone have any ideas as to why this is?

I can think of two reasons. Firstly, relic devs may have decided that old essence suits coh franchise more, for the reasons you already wrote in your post, so they decided to create a new, better version of initial engine. The other is that they created an engine under THQ that didn't have too much money at that point, so maybe they didn't have funds to include some of the functionality.