Rare mobs are one of my favorite unexpected pleasures in WoW. It's such a thrill to be questing or grinding along and see that silver dragon; it adds a lot of flavor to what could otherwise be some boring runs through out-of-the-way zones. In fact, that's an upside to the current depopulation of Azeroth: I find many more rare mobs, since no-one's been by to kill them in an hour or two. Fun fight, interesting mob, automatic green.
However, when Burning Crusade came out, it was discovered that all the Outland rare mobs were also elite. There was a blue post around the time that defended the decision as allowing them to put better loot on the mobs, making them walking treasure chests (
BC also has no world treasure chests, sadly Thanks; I guess there are still new things for me to learn in BC) . But it did make them basically unsoloable, which takes a lot of the excitement out of spotting one, at least for me: by the time I get four more people to come help me out, I don't really care any more.
Back in patch 2.3, almost all elites outside of instances were nerfed down to non-elites. This made many more quests and mobs soloable. And I just found out that all the Outland rare elites were included in this as well. Their loot may have been toned down a bit (I'm really not sure), but I think this is a great move. I'm now looking forward to scanning for rares while flying around Outland.
The question now is: will there be rares in Northrend? This was asked by a tipster whose character name I'm not going to reproduce here, because it's naughty. As of right now, no rares have been implemented in the Wrath beta, so we don't know for sure what they're going to do. My guess is that there will be rare mobs, and that most or all of them will be non-elite. It seems like it would be a step backwards to make them all elite like they did when BC was launched; Blizzard has learned a lot of lessons from classic WoW and from BC that they're putting to work in Wrath.