Originally Posted by
thesmall001
Not an asset designer, but I was there during MoP for a short while, and have spoken with many a designer about what happened with Cataclysm. Most of this is also public knowledge from various interviews, forum posts, retrospectives, and behind the scenes documentaries. Almost every quest design team/unit overran on the EK/Kalimdor updates and Vashj'ir was one of the hardest hit by this. The Earthen Ring originally played a much larger role in the zone and it was planned to be more comparable to Hyjal's setup for Firelands. As most people know, the Abyssal Maw raid was cancelled, and the datamining for that is easily available (RIP Hayven Games <3).
The raid was a mix of the dungeon we ended up getting, a bunch of Nerubian-like platforms and architecture which players would swim between, and a SSC-like section in L'ghorek with the Twilight's Hammer Cult and Naga. This was all cut long before Cataclysm actually released but close to the end of the crunch on Vashj'ir. As such there are breadcrumbs, teasers, and assets (including all of L'ghorek) which were added to the quest zone and "squeezed" into the zone narrative after it was looking likely the Abyssal Maw's 'Molten Front' equivalent and the raid were going to be cut. The blank patch of reef behind L'ghorek, 'The Abandonned Reef', is likely a reference to exactly this. (I don't have any confirmation of that, I only know about the production issues, but it's exactly the sort of thing a fed-up designer who has been told to drop tools and push to prod would do.)
Anyway, I'd imagine L'ghorek would have been sealed had they not cut the Abyssal Maw raid. That whole third section of Vashj'ir was a very late addition after the raid was looking likely to be cut. The temple structure itself is a Twilight's Hammer temple. I'd imagine that would've been where the final or penultimate boss would have resided, only becoming available at the end, similar to Blackwing Descent.