Can't tell you how many times mass air is used so often in almost every 2v2 or 3v3 and it is such a tough time to counter it. Air's strongest ability is its mobility. It is not restricted to any paths that infantry and vehicles are. They can move straight through bridges, debris, obstacles, and over hills that other units cannot follow them. Again with their speed, it makes them more nifty that they can avoid most powerful leader powers. Not effected by mines, and completely ignoring any artillery. On top of how cheap and low pop it takes to make them. While yes wolverines and reavers can make work of air. Air has the mobility to strafe and avoid an anti air army. They could move on to another base, rinse it. Army comes but the base is already gone. While air can repop and continue to another base or area immediately simply because of how mobile they are. Remember the triangle counter? You know, the Vehicles>Infantry Vehicles<Air Infantry>Air. While yes, this is true that Air dominates the majority of vehicles other than the counter units. This is not particularly true for the match up of Air vs Infantry. Most infantry cannot even shoot air, and if they can. They are mostly really ineffective at dealing with it. Air needs more counterplay, just like vehicles do, just like infantry does. I suggest a rework of the infantry vs air dynamic to be looked upon and reviewed. As well as possibly increasing the range that grunts and marines can shoot air, since they struggle at catching them in their range. Air really isnt an issue until at least late game with max tier 3 upgrades. An early game they can still be defeated having enough marines or grunts. But issue is, that those units become no longer feasible into mid-late game. So they eventually get phased out as the counter play and strats get more rigid. Their needs to be some sort of restriction on their greatest strength also, which is their mobility. I've been thinking that reavers and wolves could possibly have a splash effect where they decrease their agility and turning speed in groups, so it can dim down the hit and run strat. I also think that upgraded anti air turrets could also have same splash effect too. That way bases aren't at their mercy so easily.
Air is too dominant.