Agreed.
My first playthrough I mostly left the dragons alone. Aside from the dragon taming quest and Cory's dragon, I didn't kill any other dragons. It was a rushed PT and I finished the game at level 16 (crazy fast I know).
Then I rerolled another character for my completionist playthrough. My character this time is a fem elf mage. I wanted that keeper robe for her for role playing reason. But by the time I saved up enough money to buy the one in the Dalish shop (didn't want to destroy the grave site of my ancestors. It was a very lore bound playthrough), I was already crafting armors much stronger than the ones in the shop (as well as random drop). So the next thing for me to do then is to get the schematics and craft my own version of the keeper robe.
Alas... there is only one confirmed drop for keeper robe schematic. It's from the level 23 dragon in Emprise du Lion.
I've killed the level 21 next to it... but I'm worried once I finally get the schematic... there wouldn't be much reason to make it anymore because I would have leveled the floor with anything not a dragon.