Back in the seventies I used to see a number of Naval frigates in the US stockpile. I had heard later that the use of frigates by the US Navy was a stopgap type of a program until the Arleigh Burke class destroyers came out. But I’m not sure if that’s accurate.
I don't know about that but the Oliver Hazard Perry class frigates (FFG-7) were Anti-submarine warfare platforms, which the Arleigh Burke class destroyers can do that too but it's primary mission as Anti-Air warfare. So I'm not sure it's completely the case that they were planned as low cost gap fillers. I think instead the ability of a single vessel to have the firepower (basically the power of the missiles it can launch times the firing rate) that vertical launchers and phased array radars gave the navy in the 80s was a game changer against the soviets (where the "swarm" scenario of a hundreds of soviet aircraft coming at your battle group was a major concern) and it drove a desire for bigger vessels which could accommodate more vertical launch missile cells and a bigger phased array radars that could deliver more firepower than several older vessels.
Threats change and what's in vogue changes. The LCS was envisioned to be a post-cold war ship where the conflicts were coastal in nature - engaging small craft that you want to outspeed and outmaneuver. Now it seems the great minds think a blue water threat is more prominent but want lots of cheaper vessels. What comes around, goes around.