[Imp]

Just my view but I think the AIs air defence is fine for the following reasons.
People tend to play more with helos than fixed wing.
Also tend to think air assets are far more common than they are so AI buys more AA than it should to compensate for this fact.
Yes some formations might work in conjunction with helos but not always & many dont.
Fixed wing use in my view is used pretty rarely in the game role really only to plug holes in arty cover.
Might lead an assault as additional punch to arty.
How many planes do you think would support 3 Companys, probably 2 if lucky called in for a specific task then might linger or clear off.
If they are used in large numbers then intel would probably expect them so AAA would be beefed up in the area this is represented by the extra MANPADS etc but should probably be represented by offmap area SAMs. The player would probably get upset though that only 3 of his 10 planes made it to the map because area SAMs got them so the extra MANPADS is a middle road.

If planes helos are not used till the middle portion of the game there survivability goes up as you can detect & neutralise the remaining AAA assets. Both are then far more effective as do not have to find own targets & if they fail to destroy the target have at least upset something in the area making the area ripe for ground forces to attack.
Because all air is fast it does not mean it should lead what it means is it can reach places fast so its a reaction force. Tanks spotted over there send your planes or move helos to boost the opposing force till slower help arrives. Preferably from an angle that gaves ground forces a flank shot if they need it.
And yes the best SEAD you can buy helps a lot