Great Question to post....gratz!
First, Games I wish could get made that were fun on these genres:
1. Vietnam (I agree with the post). I have never found a war game above the squad/platoon level that worked in vietnam very well. But the mano-a-mano stuff could be fun!
2. Spanish Civil War
3. English civil War (some ok ones out there)
Games that I liked very much that are not really war games:
Kremlin: Point is to politically screw your opponents and get one of "your guys" to wave 3 times at the May Day parade. Just a crazy game of cards and betrayal...
Twilight Struggle: Great 2-person game of politics....not much dice, lots of strategic elements. Well balanced, quick play...great game.
Days of Decision: (pre WIF....love it, but can't get anybody to play with me).
It would be great to introduce some economic/industrial decision into armaments building potential. It would be great to be able to assassinate Churchill....like poor Yamamoto....or really rescue Muscilini or poison Stalin in 1940, Align Iran/Iraq in 1938....oh the Humanity of that one if it ever worked! Grab the oil of Iraq, build a rail to a port in Syria and a rail through Turkey...all in time for Poland? With a simultanious invasion of Egypt when/if UK declares war on GE? (which they wouldn't in that case--which is my whole point of what a different WWII that would be....).
War Game elements that I wish could get improved.
Personal character of majar nation leaders. I mean look at WWII! Every nation made major, major decisions based on the leader's personality. When a game is made where players take the roll of the leader, they instinctively don't make the same dumb mistakes--like not retreating as Hitler, or deploying too far forward as Stalin, or over-extending as Tojo, etc....so game elements get tweaked for game balance like Japan's merchant marine is usually about tripled historical results, Russian industry is lowered, but adverse affects of abysmal middle-management throughout the economy is not replicated well or at all (I'm not even sure how you do it other than simply reducing the economy). Ultra ....significant, yet how do you implement? France having to be reduced/hamstrung so they actually fold like the tent they were, instead of effectively deploying their robust militaryl....ect, ect,...
So political elements would be great fun, but I'd like to start a WWII game at the tables at Versaille! That's right...negotiating the end of WWI. Then do politics and economics from there until "begin hostilities" results with the start of WWII.....I'm sort of sick of rolling through Poland....over and over...and groundhog me one more time.... And then stopping at the point Germany's expansion ends because nobody wants to spend 2-3 years rolling Germany back to the bunker....(when we could just switch sides and set up for Poland again...)