Oh well, shows how behind the curve I am
I can see the reasons for upgrading. For the most part in modern combat Close Air support is primarily for Anti Armour and heavy weapons suppression.
With the modern battlefield lethality in all weapons systems a squad can command more firepower than a company in my time.
A-10 is a flying tank killer, the Commanche, and Apache are both geared more toward Armour and Vehicle targets than troops. Granted they can be very effective agianst footsoldiers, but I feel they have been developed more towards haevier targets.