So the Military unit will be better tied into the Military POP. Good
...
There were certain tricks to limit actualy decrease in populatoin of a country, also wasy to get rid of unwanted cultures in provinces. I assume this better tying in will help alleviate these exploits?
Well remember we have no direct control over pop promotion now, so we can't turn a certain culture's pops into soldiers and march them off. Minority pop conversions might be tied to your minority policy, for example, so you might not get large numbers of minority soldiers unless you have given them citizenship, and if they have citizenship you are probably less likely to want to kill them off. It's also possible that high losses from one, non-state, culture might cause dissent in that culture's pops which could cause them (and the soldiers they support) to revolt.