I've been reading stories about the increased use of airstrikes in Iraq and Afghanistan for at least a couple of years now, it seems to me that increased use of airpower is being adopted as a necessary expedient because of the ground force not being large enough in either theater. I think Tom made a comment to that effect in a thread a couple months ago.

Even with precision-guided munitions, there is plenty of collateral damage. I understand that CAS saves a lot of American lives, but it strikes me as being like the force protection argument, that in the big picture our obsession with casualty counts creates more enemies and leads to strategic failure. I also realize coalition forces are very careful with CAS, just saw something the other day on the Blackwater battle at the CPA compound in Najaf in 2004, when strike planes were repeatedly pulled back for fear of civilian casualties. But if most of the past practitioners of COIN are to be believed, airpower is one of the worst tools you can use, alongside artillery.

This always made sense to me:
http://www.d-n-i.net/fcs/six_easy_paragraphs.htm