well how many war rooms have you been in? or are you just basing your idea of a war room on movies like Wargames? As I already mentioned, for things like ICBM launches, an actual globe (or part of it) is advantageous.
even in original x-com, it's possible to have multiple ufos spread all over the globe. there is no awareness issue, since you can easily rotate the globe and track all ufos. not that tracking ufos is meaningful, since it's precise position is not important. you simply want to know which region it is in and then send interceptors after it, after which you just wait till interception occurs.
most combat operation takes place over a theater, where a 2d projection is quite accurate. the game takes place over a globe. you can't have realistic fighter interception paths or the idea of air and space in general without a spherical (or speroid). Since the primary gameplay of the map is actually the aerial interception, not having a globe is actually very relevant. you can not do things like fly over the pole to intercept a target, something which would be done in an actual aerial interception scenario.
As for the world empire building game that uses 2d, that is more of the fact that tiling doesn't work very well on 3d more than anything else.
and most importantly, a globe is much cooler than a map.
