I never understood people complaining about Batman's voice in Nolan movies or even the new one. Batman would go to great lengths to disguise his voice as to not be recognized. Using an exaggerated one that would be easy to remember, but sounds nothing like your normal voice would be a smart way to accomplish this. It always made perfect logical sense to me and it would be harder to suspend my belief if he didn't go to these lengths.
I think it's the fact that it got worse from film to film that was the problem. The voice in Begins was fine but it got coarser and much more difficult to understand as the series went on. That was really my only gripe and I think that was the problem people had most to complain about, not that he shouldn't do it anymore.