Its a fair complaint, but look at Origins. The Dlc for that was pretty scrappy and low key until Awakening. Soldier's Keep and Return to Ostagar were disgracefully short and simple for the price, Darkspawn Chronicles is playing to a very small and specific crowd that want that kind of thing, Golems of Amgarrak is just a dungeon crawl etc etc. And though its just personal taste, I can't be doing with Shale, so Stone Prisoner did nothing for me (and again was very short and simple). Shale is a decently written comic character, but feel completely out of place IMO.
So it wasn't until Awakening that I felt Origins truly got any dlc worth speaking about. By contrast, I think both of DA2's dlcs were excellent, although the fact that Hawke and co's story ended after DA2 (barring the lame cameos in this game, and Varric's complete underuse), I'd have to say that Mark of the Assassin feels a bit pointless these days. Its a fun ride, but the story threads it opens up are just either left hanging never to be resolved and/or are unceremonously ended in DA:I. Legacy for obvious reasons has stood the test of time better.
But yes, Inquisition's dlc has been awful, yet I didn't really expect much in the first place. Just look at From Software's Bloodborne, if you want to see an RPG that is being neglected for Dlc!