Insanity. If you want a ship to perform destroyer-type jobs and to replace destroyers, why the hell are you trying to do this with a frigate? It's a project that's basically doomed to failure.The key point is that, at the time Constellation was selected, the future frigate was envisioned as actually replacing some existing DDG-51 destroyers (basically, the Flight Is) as part of a broader rebalancing of the surface combatant inventory, rather than simply supplementing that existing structure with additional hulls. Whatever the merits of that objective, a shift of that nature would inevitably ruffle some feathers -- doubly so if you were proposing to replace them with a reheated LCS. From this perspective, Constellation was the largest step down from the DDG-51 baseline that the Navy was willing and able to stomach in pursuit of numbers. This perspective also helps to explain the otherwise perverse insistence on endless design changes that were so obviously hostile to the project's core objective of bringing a mature design into service on budget and on schedule.
Honestly, for all that the Legend-class is going to be a lot less capable, I think that it's just a much healthier concept going forward. Frigates aren't supposed to be able to do everything, so being more limited is fine as long as it's still good at doing frigate-type jobs. Of course, this is still the US Navy we're talking about, so I expect them to screw it up somewhere.