Well, Circle Of Life used the characters to tell an environmental fable....which related specifically to the pavilion...
it was not Timon and Pumbaa's Land Pavilion...
I am not a fan of characters at EPCOT, but if they are integrated in the right way it could be a nice enhancement... If Remy's ride was added to France...and I say Added...into the expansion plot, and not replacing any of the existing pavilion, it would make sense...Remy is a character from Paris...it is completely relevant to the pavilion.
If the Living Seas had still been The Living Seas and they had an addition of Turtle Talk with Crush....that would have been OK... But not OK to turn the whole pavilion into Finding Nemo...