If the character depicted in Batman TAS was anything like the Batman from "Superfriends", that would be a halfway decent argument. As is, the fact that the character Conroy was portraying was far more akin to Miller and Burton's Batman... as the vast majority of contemporary depictions were and have thereafter been. There wasn't a whole lot of variety in how to act the character. Now, had the writers decided to make Batman the campy product of the 60's, or even the more serious, but still rather personable Batman that the 1970's portrayed, Conroy might have elected to go a different route, but as things stand he still seperated himself pretty well from Keaton by choosing to play Bruce Wayne as an artificial-sounding caricature and Batman as a far more natural-sounding, if darker, voice. Keaton's Batman voice was a fake tough guy voice to hide the real man, whereas Conroy's was the real character.