I agree that it's important, but apparently Taylor's voice was sometimes cut a line at a time, making his voice mixed with another person's really distracting. Disney went for the less protruding option for the modern day viewer. I don't agree with that, but it's understandable.
As for the...
For those who are wondering what the difference is, here's a comparison between Deems Taylor's original voice, and Corey Burton's dub:
Burton is more or less similar, but it would have been much better to find a soundalike, to fill in the missing parts.