I have to admit (although somewhat shamefacedly) that the only raid instance I saw before Wrath launched was Karazhan. Even worse, I was only watching my roommate running around this fantastic place, slaying beasts and praying (yes, he was actually praying) for the purples to come his way. At the time, I had abandoned my first toon, a level 23 orc warrior, and I had made amazing strides leveling my holy paladin to the grand status of level 61 before taking a break. As a result, I never raided when there were massive 40-man raids or when raiding was "hard," as those BC/vanilla veterans will say, so I can't say that I'll miss some of those raids that might disappear as Cataclysm reshapes the world as we know it. As for the zones getting hit hardest by Cataclysm, I can truthfully say I'm quite fond of bidding most of them farewell. Will anyone other than die-hard Chuck Norris fans really miss The Barrens?
So what is it about WoW that I will miss when the game changes for Cataclysm? It's the fast-paced content, the extreme value of a global cooldown. Many players stress at the thought of tanks getting killed in two to three hits from a raid boss, while I thrive on the risk. During our initial attempts at Festergut, the challenge of being able to time a ridiculously strong Holy Light in between swings from the abomination to keep the tanks alive was exhilarating. As a ret paladin in PVP, I love being jumped by a rogue in a battleground. If he couldn't kill me during his initial stun, I'd probably burst him down to nothing during mine. With the dramatically increase health pools and lower comparative healing/damage planned for Cataclysm, there won't be as many hair-trigger reactions needed to stay alive. I'm pretty sure I'm going to miss the current model, in which a single GCD no longer means life or death for someone in my raid.
When Cataclysm hits, most players will miss a specific zone or instance. What do you think you'll miss? A particular ability or general function? Or are you among those who think change is good, that paladins shouldn't have bubble/hearth and it's OK if mages can bloodlust?