Why not work on alts in the meanwhile? I mean that is what Cataclysm really is - a chance for almost everything old to be new again.

I think people keeps overlooking this. Yeah, if you're only interested in maintaining your top level characters, then this isn't the expansion for you. I quickly realized that a few months ago with my own 85s. I stopped for a while (easily at that). I didn't fade out, I just plain decided the game wasn't grabbing me anymore and that it was time for me to step away and I cancelled my subscription. Then last month (I blame Blizzard's e-mail telling me I could come back for 7 free days) I decided to start up again and I've actually been having fun again by doing different things with all my inexperienced characters. And now I'm even gearing up my 85s again, too.

I'll admit my subscription is more off and on than ever before, though, and I might even cancel it again next month (as things are going to become more busy for me shortly here in real life) but that might be for the best. I like taking breaks and recharging my batteries.

But the next expansion should deliver better than Cataclysm if only because they'll be fully focusing on the future again, not the past. I'm looking forward to it.

The problem there is actually quite simple, all my alts are already lv85 and more or less raid ready. There's literally nothing left for me to do now but dailies and raid. And sadly the current crop of raids just don't interest me enough. I dunno, I joined WoW just before the launch of Ulduar and that was my first real raid, and nothing since has been quite so awesome to me.

I"m in a similar boat, I've got an 85 of each class, and a couple other lowbie alts on other servers. The issues as I see them:
1) Leveling is way too fast still, even lacking heirlooms
2) lack of content and diversity of that content: everything is linear and there just aren't that many branchs to run down. Once you hit 80, it's just the same roadmap.
3) accessible content is tedious. Dungeons have become the same "chain pull" as they were in wrath, and I think it was even quicker than in Wrath myself, but that's debateable. BUT, they're still long dungeons. Lots of trash, lots of spready out bosses down winding hallways, arbitrary fight mechanics that are are "save or die" mechanics. ("you interupt, you live, you fail just once, you wipe, have fun!")

The main issue with Cataclysm, in my opinion, is the fact that there's SIGNIFICANTLY more grinding to do in order to get anything done (compared to Wrath of the Lich King).

Considering I entered the game late-BC and only got to raid in Wrath, the amount of required grinding was... just right. Most of the reputation grinds were done rather quickly, save for Hodir, which didn't take much to finish. Once the main quest line was done, we resorted to turning in the Ulduar scrap thingies and doing their dailies, but it still flowed rather well.

We look at Cataclsym, and while I enjoy the content very much, I've noticed a few... errors... in their approach to designing this expansion:
GRINDING. We enter Tol'Barad, and.... Oh hey. Bunch of blue exclamation marks, filled with boring, "go here, kill this, fetch that" type of quests, forcing players to repetitively do these time-consuming yet boring dailies from neutral to exalted. Worse, the exalted trinket, "Mirror of Broken Images", was required by most guilds because of its high mitigation through resistance. Other trinkets were... Sub-par.
TOO LINEAR. With Wrath, playing 2 characters, one could reach from 70 to 80 without crossing over ANY quests, and it felt like playing another side of the storyline. Do I want to go from Borean, then to Dragonblight, then to Scholazar and finish up in Icecrown? Or do I want to go to Howling Fjord, Grizzly Hills, Zul'Drak, then ding in Storm Peaks? Not to mention, the instance choices were fantastic; although it got grindy and old after... HUNDREDS of runs for Emblems of Frost and such, the burnout didn't happen until the JP conversion. (at least for me) "We look at Cata, and... Oh hey, I can go to Hyjal or Vashj'ir! And then... Oh, Deepholm... I'm already 84? Oh... Gotta go to Twilight Highlands. Uldum? Why would I... Ohh, I leveled too much in Vashj'ir... I alrady out-leveled it..." And then the grind begins. On nearly ALL factions.

Not to mention... Most of the quests in Wrath had little hubs that we could go to once we got bored of the main questline, and skip most of the irrelevant finishers. Whereas with Cata, well, if you stray from the main quest, you're stuck with dungeons or good'ol' grindin'.

As much as I love Cata and raiding, I'm tired of grinding. Now, excuse me, as I help the guild get the legendary staff and work on exalted with Avengers of Hyjal... 21k rep purely from bosses sound like total bliss.

Another critical flaw that was present in Cataclysm and not in any other expansion is the lack of entry-level raid tier at release. While I can't disagree with their stance on "Epics have ceased to become epic" opinion, the fact that we received the same quality of gear as we always had (rare) even at 85 after a day's worth of nerve-wracking, heart-breaking runs of early Heroics (Admit it... Those things were hard as hell at release of Cata.) probably discouraged a lot of people. The rewarding feel of completing a bloody run through a cave filled with rocks and cultists and more rocks... was just another blue, rare-quality item. It doesn't help that they've re-used many of those models from leveling, and... Since that's what we had to wear to start raiding, as Wrath of the Lich King showed, we got burnt out on it. Fast.

With Wrath, heroics had epics at the end of the run, and most of them used unique models. The Loyal Crest of Lordaeron was a very special shield, and one of the best looking shields to date (in my opinion). Red Sword of Courage was an excellent tank weapon, and didn't get a re-tex until Halls of Reflection. Drake-mounted Crossbow is still a unique model, to this day. And who can forget the awesome visuals of Colossal Skull-Forged Cleaver, or Greed? While armors were the same as raid-quality drops, they still shone brighter than typical loot. (Planetary Helm, which used the typical Vrykul drinking bucket-helm Vs. Chitin Shell Greathelm, which used the DK starting helm)

Apologies for making this a bitchfest for Cata, but... As much complaints Wrath got (and how easy it was... I won't deny it. I PUG-raided quite efficiently the whole expansion, even seeing end-bosses), they've done some things right.