So far I think nuclear weapons are pretty underpowered and could use a boost, but I'd also like to see P&W take advantage of the fact that nations have firm physical locations on various continents and add some random radioactive fallout from nuclear strikes that would land on neighboring nations and especially on some of the nations in your own alliance that are on the same continent as the targetted nation.
Kind of make it a bigger deal in both damage and consequence. Make it less acceptable to drop the weapons, but then when there's enough to justify it, make sure there are some decent consequences that affect the entire physical region using RNG.