It makes a lot of sense for Hyatt to at least temporarily stop most Diamond status matching with the two suite nights for diamonds for the credit card signup going on. I wouldn't be surprised if a lot of people are status matching just to get the free two suite nights with no intention of staying with Hyatt longer term.
One thought on a fair way to have a one time status match for legitimate new customers who actually want to switch their business to Hyatt: what if you could qualify for Diamond for the current year if your total stays/nights already stayed plus total future booked non-refundable stays/nights the current year guaranteed you will make Diamond? So for example if you already have 15 nights stayed the current year, if you have 35 additional non-refundable nights booked the current year, then you get Diamond now rather than having to wait. I doubt many people would take advantage of this, and those who would are the ones who really plan on switching their nights to Hyatt.