So basically we have to seek out and find the last Dragonborn, my bad, the last Inquisitor.
The Inquisitor we play is the last Inquisitor so far that we know of in the DA universe, but who knows as to what they will add in the future... the same goes for Dragonborn in Skyrim.
If the Dragonborn were seeking out where the last Dragonborn before him/her went, etc.., THEN you'd have a point -- jokingly or not. But as it stands, I've revoked your gamer card.
Edit: There is actually a lot of good lore and reasoning as to why this story-arc in the DLC is taking place. I found it refreshing instead of the same ol' crap DLC packs, this actually was worth the price imo.
No game, developer, brand, publisher, series, character, genre, platform, game-control method, dlc, story, choices, etc...will be of everyone's preferred taste. However, the general consensus on this DLC that I have gotten from my friends, have read on forums in communities I'm a part of, read from trusted sources, etc.. seem to enjoy the DLC overall.