As a modder, Lar_q's comment is adequate enough. I understand it from a development position.
I'd rather have those three quality dungeons (The Knight's Dungeon, the Inner Sanctum (Temple of the dead), the Druid Dungeon) as opposed to some crappy ones and I don't care if it was promised.
And in this you are undoubtedly like the vast majority of posters in this thread, myself included. Once you are told what is going on, and if it sounds at least half reasonable, you are happy enough.
You guys are way too anal about things in the face of a game which is otherwise top quality especially in an industry full of games way too short.
You guys also forget that the dungeon was never a priority. I can imagine Larian forgot about it entirely hence why they never wrote an update about it.
In this, however, you are getting on a high horse and I'd suggest getting off before you fall would be in order.
We are talking about a megadungeon that was featured prominently in the kickstarter once it got rolling and the company started adding enticements for further funding, and was one of the highlights of update #44 last summer, when they'd gotten started on it.
It is not being anal to wonder just what the hell happened to it, when nobody could find what was, in Larian's own words,
the fabled lair beneath Phantom Forest, in the released game.
Not mentioning what had happened to it is bad communication to the backers, pure and simple, and the
reason for that failure of communication, whether they forgot, were stressed, didn't consider it important enough to mention, or for whatever other reason - is completely irrelevant to us as players and backers. That's a purely internal issue.
Hopefully Larian has learned that lesson for any future kickstarter project: If you promise something, either carry through with it or tell the backers why not.
Since the backers have given away money on a hope and a prayer to a project in the first place and tend to get emotionally invested as well, they are usually very tolerant towards changes, so long as they are told that the change has been made and why it was done, and if you don't want to risk getting into that position in the first place as a company, don't make so specific promises.