Klepsacovic expressed some interesting thoughts about Cataclysm last week. In particular he suggested that a lot of the expansion's apparent failings are not so much things that can objectively be classified as problems, but rather that Wrath of the Lich King has changed our views of the game in such a way that we now dislike features that we would have loved only a couple of years ago. Or, as he so distinctly puts it himself in his last sentence: "If WoW had Cataclysm, minus LK, it would be in a much stronger position."
This immediately sent my mind reeling. What if Cataclysm had been the expansion after Burning Crusade and Wrath of the Lich King never happened? I'm not saying that I actually wish that this was the case, but it's an interesting thought experiment. WOTLK introduced so many new mechanics to the game that it's actually quite hard to imagine WoW without them now. But what if?
This kind of speculation is always going to be vague, simply because many of Cataclysm's features are directly based on changes that were previously made in WOTLK. Take raid size for example. If WOTLK hadn't made every raid available in both a ten- and a twenty-five-man version, then Cataclysm's raids would also still only be either one or the other (and going by their overall feel, I'm inclined to say that they were all designed primarily for the larger format). Guilds that were limited to ten-mans in Burning Crusade would have felt left out by this expansion then.
However, I'm pretty sure that nobody would be complaining about Cataclysm raids being too difficult if they had come out straight after Burning Crusade, considering that BC had ended with Sunwell, one of the most difficult, if not the most difficult raid ever at the time. After that, Blackwing Descent & co. would have seemed like good "intro" raids for the new expansion. In fact, hardcore raiders probably would have complained about the content being too easy, especially since BC's attunement requirements are gone and not slowing anyone down anymore, and in this alternate universe there'd be no hard modes either (since that's another WOTLK invention). Since people like to complain regardless, they'd probably have criticised BWD and BoT for their comparatively bland interiors and lack of music.
Likewise, heroic five-mans occasionally wiping people would never have been an issue in a world where most players still remembered spending hours in heroic Shadow Labyrinth, and without a dungeon finder having trained people to expect quick runs involving little personal responsibility. We also wouldn't have started facerolling things quite so quickly if Blizzard had stuck to the old ilevel progression. Did you know that heroic five-mans didn't used to have their own tier back in BC? You basically went in there for badges, crafting materials and the chance of getting an epic from the last boss - which was only good due to being an epic, its actual ilevel was lower than that of a blue drop from normal mode!
With no random dungeon finder there'd still be daily quests for the dungeons, and people would probably feel the lack of max-level normal mode instances even more painfully than they do now. Oh look, the daily is Lost City of the Tol'vir again, what a surprise. Nobody would do the heroic daily if it was Stonecore or Grim Batol, while Vortex Pinnacle would become the new Slave Pens. I just can't decide whether Halls of Origination would be popular or hated - if you actually still had to put work into assembling a group for the daily, then getting badges for seven boss kills would present a pretty sweet reward, but people might still be put off by the length.
You wouldn't be able to accumulate reputation just by wearing the right tabard while instancing, so getting to exalted with all the various factions would actually be slightly more difficult than it is now. Dungeons would only give reputation for an appropriate faction, so Throne of the Tides could give Earthen Ring rep for example, but a place like Halls of Origination doesn't really feel connected to any particular faction and would give nothing. People would probably ask why Blizzard didn't create more alternative ways to get reputation. (Item hand-ins, anyone?)
The old world revamp would probably have been welcomed with less enthusiasm because while vanilla content already started to feel somewhat old in Burning Crusade, I don't think people would have been okay with seeing it replaced with something else just yet. The change in questing style would have felt even more dramatic and off-putting for some people, considering that there was no phasing at all back in BC, and levelling was still a little bit slower back then as well.
Archaeology would still feel incredibly grindy, but people might've been slightly less annoyed with it right after Burning Crusade, seeing how that had some very grindy aspects to it as well that would've still been fresh in people's memories.
So would that have been a better game? In some ways yes, in some ways no. I do agree with Kleps that it's all relative. If you felt that WOTLK was the pinnacle of WoW's development, then it makes sense that the ways in which the developers deviated from that path in Cataclysm won't be appealing to you. However, if (like me) you felt that WoW was at its best during the Burning Crusade era, then I think it's important to be a bit more selective with criticism of the current expansion. You don't have to like all of Cataclysm's features either, but it makes more sense to compare them directly to Burning Crusade than to whinge about things that were already set in motion during Wrath.