The US Army may be having to switch basic strategy, too. The history of American armies since Grant in the Civil War has been to tend to spend lives as though there were an unlimited source of them. Grant's casualties were 3 times Lee's, but Lee couldn't replenish his forces, and Lincoln was happy.

Montgomery in WW II was regarded as overly cautious by the Americans, but the British had a limited manpower pool, and he worked to save lives. Patton, on the other hand, was a lot like Grant.
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I have no idea where you formed the opinion that US commanders squander lives, post civil war. WWI trench warfare comparisons of US vs European generals reveal a much more troop conscious behaviour among US generals. While there was by today's standards profligate expenditure of US troops in the WWII Pacific island invasions (we had no technological advantages vs the enemy), your Patton example is totally bogus. Historians cite him for having the HIGHEST kill ratio of enemy casualties to US casualties of any US General. Troops loved fighting for him as they knew his staff would not unnecessarily risk their lives.

I claim that our post Vietnam military may often err on the too careful side (not the worst of sins). I certainly agree with your point that our tactical commanders are 2nd guessed if they have any casualties.

-p