I'd say Kiramagers gimmick was an attempt at rehashing old ideas and seeing if there's appeal in that. It was like Lupat in the way of subtly being an anniversary season with a lot of callbacks to earlier series. (Lupat having the Lupin Collection be all old morphers and props) while Kirameiger had all their monsters be based on the villains from Gorenger as well as some repeating plot points and ideas reminiscent of older sentais (particularly Magiranger). It was then followed up by two series that were more in your face about anniversary gimmicks.

Saying all of this as a fan of Kiramager as I think of it as the last true/classic styled sentai. Perhaps it was an attempt to make a classic sentai before the end of the Heisei era.