I'm perfectly willing to argue about this all day, but The Witcher 2 had less character development (gameplay wise,) actiony combat (with no combat stances,) and a simplified alchemy system. The quests were still not that complex, but that's not too far different from the Witcher 1.
1) I'd rather have less character development (gameplay wise) and a fully fleshed out main protagonist with more depth than any DA:I character, than a tame, domesticated and average one, as one of the forum members accurately described the Inquisitor.
2) gameplay and mechanics-wise, TW2 is an action hack'n'slash game. The developers were open about it from day 1. IMO the story, quality of writing, and coherency of the gameworld far surpass anything DA came up with (which is no mystery since the game is based on a celebrated series by Sapkowski, and developed with his help).
3) don't really know why you pointed out alchemy only, as it's just one division of crafting. Anyways, alchemy is as it as because Geralt is a witcher, and they prepare a handful of special concoctions (unique for witchers) for a given encounter. You also have traps and bombs within the alchemy concept. In regards to potions, TW2 is at least realistic (if one can really use this word); they are toxic and you cannot just drink them in the midst of the battle. DA:I has potion quaffing in your opponents face - in this regard, DA:I alchemy is more hack'n'slashish than TW2.
4) you want to compare complexity of storylines and quests? Do you really want to engage in that battle with DA:I having the most generic quests you can think of?
On a side note, I've noticed there is a group of forum members dissing the hell out of The Witcher series anytime they have a chance to. Is it because the two series are kind of competing and you feel the urge to protect Bioware with all the zeal you can muster? Both series are great, it just happens that one of them is going downhill.
Peace.