NO icons in AH main arenas is a terrible idea.
First, there is the practical aspects of identifying friend from foe when they are flying identical planes including the paint schemes.
Second, the realism. This is one of the cases where an unrealistic game mechanic makes some aspect of the game more realistic. As already mentioned by someone above, due to screen resolution and size limitations, we are the equivalent of pilots with terrible eye sight that should never be allowed to hold a stick or even drive a car. The icons are a poor attempt to compensate for that, yet it is the best solution anyone has come up with. Over the years HT had tweaked it so the icons convey the minimal required information and give as little help otherwise. This is why the tags appear below the planes and not above. This is why tags give specific model information only at short ranges. This is why the range indicator resolution changes with distance (from 1000 yards, to 200 yards, to single yards). This is why we get a + or - indicator when the relative speeds are high. All these are meant to help players with poor eye-sights - that means EVERYONE relative to real life. Removing the icons makes it a fun confused game for one session, but otherwise it makes combat LESS realistic.