I always thought Lion King uses a flat stage with a lift to rake it for certain scenes. I cant imagine watching it with out that raised platform. One of the designers commented that with out this raised section (they were calling it the mountain) pride rock just does not look right.
as for Wicked, I never liked the 2 sections that slide on to act as platforms for Morrible. I guess if I had not seen the Broadway version they would be ok. To me those 2 units just come accross as unnessessary, either put in the balconies or block the scenes differently. Mind you there usualy is plenty of room between the prescenium, the geers and the speakers that they could have integrated some sort of balcony, but i guess it woulf cost more. Overall I dont mind cutting Morrible out and just using her vioce, and I would cut boq and the lion all together.
http://www.flickr.com/photos/27199361@N08/ Phantom at the Royal Empire Theatre