The uniforms the Soldiers were issued were some lowest bidder crap. Much worse quality than the ACUs, which aren't exactly famed for being resilient either.
This all gets back to the Global War on Fashion. The Army is completely in the grip of too many generals sitting on too many panels, all fighting to make their next star and get set up for when they retire. The ACU was a dismal failure, and their efforts to move on past it are schizophrenic and random.
As to the pants falling apart, you get what you pay for. It's unfortunate that this endless uniform infighting results in less money for what needs to be purchased, so they skimp on the quality. But much, much better stuff is available.
I’ll bet you $5.00 when the suits come looking to cut money (because of the swell Boehner/Obama Debt Ceiling deal), this is where they’ll squeeze more savings, while continuing to buy $600 toilets and coffee pots that will brew a cup of joe at 10G on the bombers.