I'm on deck with two observations made repeatedly in this thread - that MCC could have used more Muppet characters in the main roles (including the ghosts) and the basic observation that it should have been "much more Muppety." I know the creative team was trying to stay close to Dickens' original story but the result left me somewhat cold when I saw it in theatres in 1992.
Knowing that it was too soon to recast a lot of Jim's and Richard's characters, I still submit that other Muppet faces could have filled in several of these roles. For example, I think Jerry Nelson's Pops would have worked better as Jacob Marley than the Statler-and-Waldorf brother act (which would have also saved us from a song that still makes me cringe years later).
Glad to see heralde and Drtooth reference Mickey's Christmas Carol in this thread. I think that featurette made much better use of its stable of characters than MCC did with the Muppets/Henson cast (realizing, of course, the difficulty in meting out these roles so soon after Jim and Richard left us). I mean, if a one-dimensional buffoon like Peg-Leg Pete could do a convincing Ghost of Christmas Future, surely there was a Muppet that could command the same gravitas. (I'm looking at you, Uncle Deadly.)
Anyway, I don't want to be too hard on Brian Henson and the early-'90s Muppet crew for a sincere, honest effort. I have teenage nieces who were introduced to the Muppets through MCC and still cite it as a holiday favourite. If the movie accomplished nothing other than that, I would still be grateful - and, of course, it accomplished so much more, and continues to do so to this day.