Oh of course, even a disappointing Muppet appearance is worth at least watching rather than missing altogether.
They really could/should have done more. I mean at least a LITTLE something more - have an extra little surprise in the song or something interesting with the ending. I mean when you have a band with such a visually innovative reputation (in both vids and live appearances) and it's announced ahead of time that they're performing with the Muppets and it's just Animal on drums, there's no way they couldn't be aware they were setting up a lot of people for disappointment. They could have had Muppets come out and do a pyramid for the last verse (think how much of a crowdpleaser that would have been if you weren't expecting it) or an after-comment from Statler & Waldorf - anything really.
And if the live performance was going to be comparatively bland, would it have killed them to show a clip from the video like going into or coming out of commercial with the caption "coming up - OK Go with The Muppets" and people could have got a glimpse of the fabulousness that is the video.
Oh well, it just goes to show that when the pig spends a show locked in an office, the fabulousosity potential is muzzled.