This topic is a bit old, but I totally support the motion. In NW, you knew 1 or 2 friendly regiments that you'd practise with and that was it. But if regiments have to pick sides, then everyone automatically feels drawn to other regiments of the same nation.
In Naval Action, people were always friendly with fleets from the same nation or allied nation and rival with fleets of ennemy nations, the only exception being rogue fleets (like PAIN in the Dutch Republic) and neutral/trading fleets.
You split your community in 2, but these 2 groups are a lot closer internally. NW is like the HRE, a bunch of independent, fractured states allied with a few neighbours. Now divide these small states between Prussia and Austria. You have split the HRE in two, but these 2 parts are more unified than the HRE ever was, because they work for a same common goal: their country.
Hope my stupid hypothetical scenario helped illustrate my point, and hopefully AGS will divide the regiments between UK and France.