Cataclysm is the first WoW expansion since The Burning Crusade to get a pair of new playable races. This isn't exactly news*, since Cata has been out for almost half a year. Since that time, however, we've had plenty of opportunity to get used to Goblins and Worgen out there in the field, so I thought I'd do a bit of compare/contrast with Blood Elves and Draenei, and how their introduction was handled.
The Burning Crusade - Shoehorning Made Perfect
When BC came out, Vanilla was still fresh. The old content wasn't quite so old or creaky, but Blizzard did learn quite a bit about how to pace content. Outland's instances and questlines were more streamlined than Vanilla, and nowhere was this new approach more apparent than the new BC races. The Blood Elf and Draenei starting areas had a better flow to them than the old Vanilla ones, and when you finished the Ghostlands or Bloodmyst Isle you were well indoctrinated into each race's viewpoint.
Then you left those starting areas, and returned to the world of Vanilla.
Vanilla was almost exactly the same as before, with the exception of the lone Blood Elf or Draenei in a quest hub. Occasionally, that NPC would have an actual quest chain attached --the Blood Elf at Freewind Post or the Draenei at Forest Song, for example-- but mostly the NPC was a reminder that yeah, there were a couple of extra races in Azeroth. The anachronisms of the Blood Elves in Azshara remained, causing no small amount of confusion to people joining WoW in BC or Wrath. "How come the Orc is so upset about trusting them?" I once asked Soul. "Aren't we all part of the same Horde?"
"That was a Vanilla quest chain," he replied, "and it was never updated or removed."
Vanilla was --by and large-- not well integrated with the two new races, but Blizz compensated for it once you reached Outland.
BC wasn't entirely about the Sindorei or Draenei, but there are plenty of times when it sure seems that way. The new races weren't there for decoration, they were an vital part of the entire story. After spending most of your leveling time in Vanilla forgetting the lore of the starting areas, Outland was almost an overdose on the stuff. While the Orc lore took center stage in Nagrand, Hellfire Peninsula, and Blade's Edge Mountains, were it not for Kael and the Blood Elves, the Horde probably wouldn't even be there. The same goes for the Sons of Lothar and the Alliance: nice, but not necessary. The arrival of the Draenei aboard The Exodar made it necessary.
Cataclysm - Well, That's One Way of Integrating Things: Blow it all up!
After passing on Wrath, Blizz added two races into the fold for Cataclysm: Goblins and Worgen. The reworking of the Old World afforded Blizz the rare chance to seamlessly integrate the two new races into Azeroth, and they ran with it. They did a great job of fixing the problems with plopping new races into an unchanged basic game, and they are to be commended for completing the unfinished backstory on the Worgen.
Once you reach the Cata zones, however, the two new races simply become invisible.
Sure, there's Goldmine the NPC and the Goblin outpost in Twilight Highlands, but outside of that, where are the two new races given any significant face time? I think there was one --one!-- Worgen questgiver in Vashj'ir, but that was it.
Okay, I understand that the emphasis in this expansion is on the Earthen Ring, the Guardians of Hyjal, and some of the original races, but come on. Draenei (and the Taunka Shaman, Toshe Chaosrender) get more face time as members of the Earthen Ring than Worgen do in the entire set of Cata zones. And the Krazzworks in Twilight Highlands could easily have been a neutral Goblin outpost under attack by Twilight Drakes. The new races are merely there in the new Cata zones; the main storylines in Cataclysm have passed them by.
This begs the question: were the two new races even necessary for Cataclysm? After all, the reworking of Vanilla WoW, which was so vital to incorporating the Goblins and Worgen into each faction, is available to anyone who plays only the basic game. There is no Cata-specific content that emphasizes their racial story, despite the obvious potential lead-ins the Worgen could have had in Hyjal (or the Goblins in Vashj'ir, who could have had some of their shipping fleets sunk by the kraken). Instead, the new races come off as being the Scrappy Doo of Cataclysm, which is a shame.
*Yep, and my nickname is Sherlock, too! Okay, not really. Anyhoo....