I've stayed at most of the locations you discussed in Chicago and agree with your assessment. Chicago has one of the best collections of 5* hotels in the US (langham, WA, FS, Pennisula) and I agree Hyatt needs to up the ante on PH.
However, while the other hotels are not great for diamonds, they are well priced and well located for the nonDiamond market and likely more profitable for the chain.
I hate HP b/c I find no value as a Diamond. I don't want the 500pt if it's a breakfast I won't eat. However, I think it is a great value for nonDiamond families with all having jr suite setups and free breakfast. I think that is why they recently open 3 HP in downtown Chicago.