The fundamental issue with airpower in Ukraine vs Russia is that Ukrainians have both good covering terrain (muddy forest) and have the actual Russian version, not export version, of air defense. However, they have very weak strike capability of their own. So what they can do is deny and reduce Russian sorties, but not carry out their own.
This produces the illusion of airpower being unimportant when in reality it is supremely important. if Ukrainian SAMs were weaker Russia would be carpet bombing them and if Russian Air Force was weaker Ukrainians would still be able to hit their field troops with helicopters, drones and attack planes.
Artillery is actually one of the most important capabilities for a ground army. It produces sustained, long ranged, BVR firepower. There are very few systems capable of sustained BVR firepower other than artillery. Airstrikes can hit BVR but they aren't sustained. Tanks and helicopters are short ranged. Only naval ships can provide this too, but obviously, naval ships can't go on land. So that leaves artillery.
