Christening Wally West and/or Bart Allen as The Flash was never necessary. DC already had an established character, Barry Allen, as The Flash.
Unnecessary perhaps, but we got some damn good stories and characters out of Wally’s run as the Flash. We also got Impulse. How likely would DC have been to introduce Impulse if they still had Barry as the Flash and Wally as Kid Flash? And it’s hard to imagine Young Justice without Impulse.
Similarly, it was unnecessary to create Barry Allen in 1956. DC could easily have pulled Jay Garrick off the shelf, dusted him off, and revamped him, but they chose instead to create a new character using the Flash name. And this was someone who carried three titles for the better part of a decade!