Because I'd say it's rather CAS (un)Realistic Battles, the current 'ground' naming is misleading.

Arcade battles with tanks do feel like Ground Arcade Battles: tanks and TDs are the main classes, they decide the outcome of every match, and airplane call-downs are just a funny perk to diversify your experience a bit; neither OP nor that much toxic, as helicopters die to SPAAs pretty quickly and airplanes only use unguided bombs and rockets strong against targets that stay for too long in one place or have little to no armor.

Simulator battles with tanks do feel like Ground Simulator Battles too, unless it's 10_2 where helicopters get thermals, auto-trackers, Hellfires and other strong ATGMs, and airplanes can use early TV- and laser-guided bombs and AGMs, not to mention 11_2 where air can utterly destroy all ground with tons of Spikes, Kh-38 and the likes. All the rest lineups (9) barely perceive the existence of airplanes in the skies above the battlefield, those whose best usage is a flying observer providing intel for squadmates/allied team to outplay opponents in tank vs tank confrontation rather than trying to perform CAS themselves and risk dying to a single enemy SPAA pretty quickly. One illustrative example is my personal record of 6 ground kills in WW2 bomber (Do 217 E-2) with the first place in the team, the most kills of all players in the match...and the team still losing as it's the success of enemy ground that captured all 3 objectives and just playing defensively, with T77E1 not letting me come close to bomb them out of their positions https://imgur.com/a/0HvsL8Z Sure, it's much more difficult for potential enemy fighters to shoot down an enemy bomb wagon, but so it is difficult for a wagon to spot, identify ground targets, prepare a route of strike, bomb precisely and not get shot down by heavy MGs and cannons from ground (you can notice it was the 'friendly' Wirbelwind who managed to confuse me with some aircraft of the Allies somehow, otherwise it could have been zero deaths and 1-2 additional ground kills for me, but we would have still likely been defeated, cos again, tanks decide whether you win or lose most of the time, especially on city maps).

But when it comes to realistic battles...it's all about spawning your first tank, capping an objective, making a kill (even better if you use a light tank to benefit from active scouting) and J'ing out to just hop into some Yak-9K, potent striker with powerful autocannons or a fully-loaded bomber and wreak havoc on people who'll be demoralized in their next spawned vehicles, or spawn a useless SPAA (those are many times less effective than fighters or even bombers with fixed offensive armament in dealing with air), or just ODL, the one-sided slaughter being further enhanced by more of your allies spawning additional air to cover your from airborne threats, bomb even more enemy tanks or supress annoying SPAAs that although slightly, but do disturb you nonetheless. And it all ends up with your entire team steamrolling the foe right to their spawn, even if the latter at some moment had more tanks and more potential to control the battlefield and objectives. The few allied tanks or fast SPAAs capture remaining objectives, and proceed to shoot the enemies that spawn at their base from safe spots, with SPAAs as the last 70 SP option being completely useless against armor on tracks that comes to roll it into mud...a classical scenario, isn't it?

So why not rename the mode finally, so that newcomers will have no illusions about what awaits them there? Let them know the actual gameplay is CAS feasting on ground as soon as it appears with the best available ordnance (although I saw in some videos helicopters with pure rocket loadouts blowing up generation 2 and 3 MBTs as well and safely returning to their helipads, yikes) it can drop on their heads, and ground itself serves more as an auxiliary force, meat shields, cheap cappers, and scouts that help identify a new target for the air. By no means a force on its own which is allowed to have fun fighting their own kin and be effective/decisive tools for victory.