Personally I like the system as it is. It works in DoI because DoI is a better game. If Sandstorm gets unfucked and becomes a high lethality tactical shooter, people will stick together and work together naturally as it will become the way to win instead of the current zergy zoomfest.
Why not split the responsibility for fire support? Give the commander the choice of what to call and give the observer the choice of the location? Then extend the proximity range they need to be from eachother to roughly shouting distance (or just make it infinite and have the request over the local radio) and reduce the number of observers to one.
Commander uses a radial menu: "Call in a gunship!"
Commander's menu goes into a 10 second cooldown. Observer has 10 seconds in which to call that specific support.
Observer gets out the binoculars and mouse1's the location. No need to be exposed while fiddling with their own radial menu, then the voiceover plays to confirm.
All fire support cooldowns should be easily visible to both parties ideally too as it'll enable randoms to coordinate.
Not something I feel overly strong about, but the main complaint which gets reiterated a lot is the observer being the commander's pet. This splits the decisionmaking encouraging communication and justifiably extends the operational range of the two players increasing convenience.