This is a tiny soap box, but it's my soap box and I'm going to stand on it.
Doing a good job of being a muppet performer doesn't just mean sounding exactly like the person who previously performed the character.
While there has been lots of praise for the new Muppets special, the one stumbling block that people can't seem to help commenting on is that Kermit doesn't sound like Kermit. They say that so many people can do a spot on Kermit impression, so why didn't they go with one of those.
But a muppet performance isn't just doing a voice. The person doing the voice is also controlling the character. It's not just that Kermit needs to sound like Kermit, but he needs to act like Kermit, move like Kermit, get frustrated like Kermit, freak out like Kermit and everything else like Kermit. We're looking at a full physical performance that is consistent with the character.
What's more, The Muppets also appear live from time to time. In promoting this very special Muppet character were trotted out to give interviews on a press tour.
Matt Vogel, the current performer of Kermit, not only has to bring Kermit to life capturing all of his mannerisms, he also has to respond in character to questions and unexpected moments and keep the character consistent the whole time.
I know that Kermit sounds a little different now, but it still felt like I was watching Kermit. Any the way that people sound change. I know Kermit doesn't sound exactly the same way he did fifty years ago, but everyone else who was putting on a show in 1976 sounds a little bit different today too.