Exactly. I get so bugged by people saying "Where's X? I can't believe they don't show X anymore, and they only show Elmo" (or Pepe if we're talking The Muppet Show). and THEN going back and saying, "Ugh! That's what they sound like?"
Recasting muppets isn't easy. You don't just have to do the voice, you also have to get the personality down pat, and have a symbiotic relationship to the character. That's why some characters bounce around from performer to performer, and in some cases, never get recast. Even Elmo went through 2 other puppeteers before Kevin Clash made the character what he is today. Sometimes we'll get lucky and find someone right away who can sound approximately like the characters in question... Eric Jacobson has taken to a lot of Frank's roles, and in some of them, you can't even tell a difference (He is flawless as Grover and Fozzie)... and sometimes you get the Scooter situation, where he was bounced from Brian Henson to Rickey Boyd to David Rudman.
And Besides, we've only seen Eric's Guy a couple times... a PSA for Ready to Learn and this episode. I'm sure after time, if Eric continues the role, he'll fit more comfortably into it, as he did with Bert, Piggy, and all them.
That said, it took them HOW long to get Gilbert Gottfried into a Muppet Project why?