DAO:s overall styling of cities, clothing, armor and weapons, religion, music soundtrack and tavern gave the perfect feeling that it could have taken place in medieval Europe which brought its charm. But that may be the reason why I feel like DAI has lost all of it.
Origins doesn't cover nearly as much ground as Inquisition does either, since we never leave Ferelden. I don't see any meaningful difference in the overall design of the interiors of homes and taverns like in Redcliffe or Haven than what we saw in Origins, but we obviously never saw anything of Orlais until DA2 onward, and frankly I think they've been more consistent about this than people give it credit for. If anything, what really changed is that Ferelden no longer looks like blood-splattered oatmeal. I don't think that Inquisition's lost the rustic appeal of places within Ferelden, though it's unfortunate that we don't get proper cities like Denerim.
Regular people throughout Ferelden still seem to wear ordinary peasant clothing similar to what we've seen in Origins and DA2, so I'm not sure what the big deal is there. As for armor, I'm of the opinion that the armor designs from Origins are vastly inferior, so all's I can say on that end is good riddance to bad rubbish. For me, trying to find decent looking armor in Origins was like a conversation with a sober Oghren: few and far between, especially if you were a dex-based rogue (infinitely worse if your rogue is female). When I see criticism of things like Inquisition's helmets and such, I can't help but think back of the vast wasteland that was Origins' offerings.
Personally I think Origins' general design gets a bit more credit than it really deserves. There's a lot of charm to the whole thing, but first and foremost my big draw to the game is the story and the characters. The rest is, to me, disposable, and would gladly do away with it in favor of something more refined in its aesthetic.