I do not support such a thing as this, my reason being that once you annex something like France, the game becomes total war against all other nations because they'll hate your life and form a massive coalition against you. That being said, that would probably be a reason for Paradox not to do that, and instead work a bit more on diplomacy and trade.
Besides that, everybody seems to complain that you can only take 2-4 provinces at a time, when they're sitting there and trying to take god-like provinces, in terms of base tax, manpower, etc., and not taking the provinces with less base tax (because if you build buildings, you can make those provinces better than they are). I've taken about 5 or 6 provinces from Serbia in a war, and that was with only one claim. When you see "I can only take 2-4 provinces," I see "I'm trying to annex Milan when it still has Lombard," etc. To me, 5 or 6 provinces felt a little extreme, especially for the time period. I feel that 4 provinces per war is fine. I'm sure that those of you who like war have realized, with the massive coalitions against you, that if you declare war on one nation that's in a coalition against you, you can take what you want, hope that someone else joins the coalition against you, and declare war on that nation and take more land? There are so many different ways to exploit the system, and you still complain, when it shouldn't even be that way in the first place.
So, to summarize, I would think that diplomacy needs more work than war (other than fixing things like the coalition exploits. Those should definitely be worked on. Maybe have a cool-down on when you can fight a coalition against you).