Hmmmmm why can they see an Airplane from 5k out? seems to me that looking up in the sky one would see it approaching or circling, the features been in the game for as long as i remember and all of a sudden it's an issue 
Quite so... More of the GV whining we saw from Red Storm/Krupp Steel, no doubt.
Moot, it's not so easy to spot and ID GVs. They are all square little boxes of pixels with treads. Unless you get in under 500 yards and use max zoom actually making out a profile while flying is nearly impossible.
On top of that you only get icons showing up right as you're in lethal guns range. Further, most times I'm spotting GVs at a spawn point that are attacking my field, I have to circle several times. The icons stay relative to your screen so if you are tilted the icon can dig into the ground. It is also obscured by trees. That means not only do you have to get close, often you have to stay close to figure out how to read that icon.
It's FAR from the sitting duck wounded target you portray it as being.
Also: Keep in mind GV's zoom from the main gun is much stronger magnification than the zoom from a plane's cockpit, last I recall. On top of that, the zoom/view systems are all being redesigned by HTC and your entire point may be moot anyways.