NPH is overrated and overexposed, so I think it's wise they went with some one else in the last one. Heck, even his cameo and him remarking, "I don't know why I'M not the one hosting this thing" seemed force... but then again, some of the celebrity cameos seemed a little forced any way, but then again, the Muppets needed star power to help their telethon get noticed, so they needed just about any relevant celebrity they could.
EDIT: Charlie ziffeled me, I was responding to muppetlover123's previous post.