Do you want more light hearted stuff like Opera, or more randomness in raids, like Prince? Here's what Drysc says:

I would agree that the light-heartedness of the Opera is a really refreshing change, and it was great there's a place for it in Karazhan. In a world of demon-infested castles, dungeons, and dark caves it's not every one you can create such an event and have it fit and make sense. So, I think the Opera event was more a product of location than of the desire to make something a bit more whimsical.

As for Prince Malchezaar and that fight, yeah it's got the whole random thing going on with the infernals. However; you can mitigate the randomness of their drops any number of ways. By being over-geared you can certainly deal with the problems better as they crop up, but then really why are you fighting Prince? You can also track the fall of the infernals, have a barker that's good at watching them and able to anticipate their placement. Or, use one of a couple different placement strategies that make it almost impossible for an infernal to interfere. The last one being the most popular these days I suspect.