When someone creates something as new and innovative as Jim did with the Muppets, it would be hard for anybody to be able to match the level of creativity. The post Jim Henson muppets are indeed different from when he was involved, but that's to be expected. (To be fair, it wasn't just him that brought them all to life, and I'm not sure how much input other people had in their creation, but the Muppets always have been and always will be considered the creation of Jim Henson.)
I thought MCC and MTI still carried the spirit of the Muppets, but MTI came out in 1996. As has been pointed out, they've done very little worthwhile in the past 10 years or so. I wasn't all that impressed with MWoO myself, but they're definitely headed in the right direction. I think they showed with MCC and MTI that even without Jim, the magic of the Muppets can still be captured. It's mostly just a matter of finding it and tapping into it again.