Broadly speaking, a lot of the general pre-Crisis stuff they banished from Superman and Wonder Woman works perfectly well in modern times. And rebooting them and creating those needlessly difficult story issues harmed them in the long run more than him.
By what metric did it not work?
And by what criteria do things like Superman being Superboy as a kid, a clean connection to Supergirl, Krypto and a clear connection to the Legion have "not place in the modern world"?