My recon planes are always shot down!

[Griefbringer]

Having served in AA unit in military, I do not see anything unrealistic with frontline AA weapons being high priority targets for artillery.

In game the spotter planes cannot call artillery fire, but in real world they could very well have radio link to ground artillery control, enabling them to issue coordinates for targets - and I presume they would consider any AA gun in close vicinity a high priority target.

Also, I don't really think that clearing the way for ground forces was really what the air units were doing all that much in WWII - attacking units close to the front line ran a risk of strafing and bombing friendly units (this happened historically, and it can also happen in game). Rather, they would be taking the battle to the depth and attack reserves, artillery and supply units in the rear, to prevent them from supporting the front lines.