I think the consensus was that the loot drops for an adventure would be +/- 3 levels e.g. level 3 to level 9 loot from a level 6 adventure... Just dropped Silvery Nuggets from a level 21 mid-adventure chest, so it looks like that range needs extending since the expansion. What levels are you guys seeing on these new adventures?
AotA was about rocks and sticks and ancient stuff. Cave drawings aren't portable. A citadel implies artisans and technology - hence, treasured goodies. Level 17 treasures cover the range to 21, so it wasn't necessary, but the Crown of Chaos should be allowed to drop.
If you consider treasure as just a source of cash then you might ask why...if you're chasing one of everything then you might well ask why not?
Sorry, I meant that question in response to 'surprise,' as a question about expectations - not that Citadel treasure wouldn't have made sense. And Veza... no. There are plans.