After reading opinions on both sides of the issue including smart guys like Lowe/Pelton who seem to think the smartest course of action is to match, I still think the Jazz should let Hayward walk. To me the bottom line is the Jazz will have $60-$80MM per year depending on the cap/tax line to buy as much value as possible. Using $15MM of that space to pay Hayward more than he's worth just means the remaining $45-$65MM has to be spent that much more wisely to create the surplus value necessary to make the Jazz contenders. The easiest way to generate surplus value is to have a megastar like LeBron, KD, etc. who is worth way more than his max contract slot. The Jazz don't look to have a player of that caliber right now, so they're already a bit behind the 8-ball--they need to spend their resources even more wisely to make up that gap, not throw away a few extra million per year b/c they're afraid of losing an asset "for nothing."
Relatedly, the losing Hayward "for nothing" argument also rings hollow to me. It ignores the idea of opportunity cost. That is, the $15MM the Jazz would spend on Hayward could also be spent in innumerable other ways--everything from renting out the cap space for assets, to doing what Dallas did last year and signing mid-level FAs like Ellis and Calderon. Some of those ideas could prove better than ponying up the cash for Hayward; others could prove worse.
To me the bottom line is that I don't think there's any chance Hayward is the smartest possible use of $15MM dollars. As a small market team, it's imperative that Utah make every dollar count, both in the present and going forward. I'd prefer that they take a chance in either trying to fill out the roster with other, cheaper FAs and/or renting out the remaining space rather than settle for the safe, but 99% likely to be mediocre outcome of paying Hayward the max.
All of that said, I like Hayward both as a person and as a player. If he winds up back in Utah, I will hope he proves the above analysis wrong and if he goes to Charlotte, I will wish him nothing but the best.