Fair enough. I guess there will be times when the Hyatt turns out cheaper than staying that night at your deluxe resort and in those instances, a person needs to weigh whether they want the cost savings or the convenience. But similarly, I'd imagine there are times when the Hyatt is busy (for whatever reason) and their price is high and an individual has a promotional rate on their deluxe room. In the latter scenario, the price difference isn't as great so the reasons for staying there make less sense.
But at the end of the day, the benefit (or lack thereof) of staying there will vary for everyone depending on their WDW resort, the Hyatt price that night, time of year, etc.
You're contradicting yourself. If you stayed at a moderate resort on your arrival night and wanted to transfer to your deluxe resort the next day, you simply pack up and leave your bags at bell services to transfer them, and then head out to the parks. When you're done at the parks, you just head to your deluxe resort and your bags will have been transferred there for you. It's easier than staying at the Hyatt - where you still would have to pack up and transfer to another hotel 30 minutes away.
Now, if you're a self-declared "hotel snob" and just won't stay at a moderate, then that's a different scenario and personal preference.