I'm assuming you don't know that Jim Henson specifically wanted Steve Whitmire to take over Kermit if anything happened to him. If Jim felt like Steve was the right choice for Kermit, I think we should all think he's the right choice.
I understand that Kermit doesn't sound the same now as he did back when Jim was alive, but Jim's Kermit and Steve's Kermit are two totally different interpretations. Steve says that all the time. Jim's Kermit is classic, we can all agree on that. Steve's Kermit has an acquired taste (figuratively not literally
) because he's added so many new layers to the character. If you watch enough of the "new" Kermit he starts to grow on you, but for anyone who hasn't followed every single Muppet production since after Jim's death, I get that it's hard to get used to "new" Kermit.
(Just an FYI, Steve is only about 10 years away from puppeteering Kermit longer than Jim Henson did. In Steve's 25 years as Kermit he's made more appearences, movies and half as many TV show episodes than Jim's Kermit did ...)