While a pop increase won't have an impact at the time, it will have a very small impact on manpower income. I don't think it's necessary personally, especially since that would create a snowball effect that could be hard to predict the impact of.
Actually, its easy to predict the impact of it, since it subtracts a set amount of mp per pop 1,5 to 1.
After having light on field for 20 minutes, you'd be able to reinforce 1 gren less.
Pop changes make sense exclusively in pop heavy units or spammable units, they do literally nothing to units that die fast and never are being built more then 1 per game.