Well, you know, Kevin was having similar problems with Elmo, but the circumstances were different: Kevin was the one who made Elmo the established character he is today. Even so, as Kevin got older, Elmo's falscetto wasn't quite as high as it was when Kevin was younger. It happens. Abby is sounding lower than she did before; Telly sounds lower than he did before; even David's Cookie Monster voice is noticably different than it was when he first inherited the character.
Even before Mel Blanc died, almost all of the Looney Tunes' voices sounded like a register or octavive lower than they used to back in their glory days of the 40s and 50s.
Completely different. Elmo still sounded distinctly like Elmo, Abby still sounds distinctly like Abby. Sure there might be slightly varied. Even Caroll's Big Bird sounded a little bit different 10 years ago than it did in the 80's. This is natural. Voices will change. Steve's Kermit changed a ton from The Muppets Celebrate Jim Henson.
With Mel Blanc, sure his voice changed. But it wasn't noticeable to the average viewer. Daffy Duck was still Daffy duck. It was a natural progression. Even the current voice actors for the Looney tunes know how to distinctly capture that same feel.
Matt's Big Bird doesn't distinctly sound like Big Bird. The same way let's say Ryan Dillon's Elmo sounds like Elmo.
I realize voices change, but that doesn't mean just because Matt's voice changed means he's still the right fit for Big Bird. All the other examples still sounded like those respective character. Big Bird sounds like Barney the dinosaur. Matt used to sound like Big Bird. Now he doesn't. It's as simple as that. It's noticeable. Unlike those other examples mentioned.
I'm not saying there's an issue with his voice changing. I'm saying there's an issue with him playing Big Bird. If it doesn't sound or feel like Big Bird. It's problematic.
Had Matt's voice changed and he still sounded like big bird, I wouldn't have a problem with it. So you really can't compare the situation to those examples.
If Kevin's voice to the point where it didn't sound remotely like Elmo, I would say the exact same thing.
We're not talking about the fact that Matt has no control over his voice changing. We're talking about the fact that he can't do big bird.