Some people speculate..
1) Maybe it has to do with the financial infrastructure of the global munitions business. No longer an industry segregated by countries, today the same groups collaborate on profiting from both sides of a war.
BLU-82B costed 20.000 USD back in it's days. Has been good enough against Tora Bora, Afghanistan
GBU-43/B comes like 14.600.000 USD there is some visible incline in pricings
Pricings for Tomahawks resupply currently rising, multiplied by numbers needed (<30% hit rate)
Not that much of a war against terror anymore, more like a war against budgets