Every once in a while I'll see an alliance raid or dungeon boss fight where it's obvious they wanted to do something specific with the fight mechanics but then just didn't, maybe because it would have been too hard.
Often I think to myself, "what a wasted opportunity!" But then I think, wait, no, that will probably come back in a high-end raid. And with ultimates drawing from existing content, it might come back with another version of the exact same boss.