I didn't think of the taint as being a result of blood magic. I mean, the conventional story is that it was caused by the magisters' sin, but magic causing diseases that can spread to people who haven't been in direct contact, that struck me as new.
I also didn't think the aravels actually flew. I guess they're more hovercraft, lol. I do remember people in Origins saying that the trees would part for the Dalish, but I figured that was keeper magic. Which I guess the aravels are, also. And in contemporary game time, clans are getting bogged down from trying to travel overland, which probably goes back to magic declining among them.
It's kind of odd that they say that about the Dalish whereas in DA2 there was ambient chatter about there being more mages than in the past. A leveling out between elves and humans?
*LAST FLIGHT SPOILERS*
It's been a few months since I read it, so feel free to smack me with corrections if I remember something completely wrong. 
The rage plague that wiped out (almost
) all of the griffons is very interesting. I almost consider it foreshadowing for the reveal about how the Blight started. Blood magic seems to have very interesting interactions with the Taint, and both obviously relate to blood. Darkspawn emissaries use blood magic, don't they?
Power from the Taint and from the blood, (which has the Taint) but nothing from the Fade.
Perhaps one of the gods in the olden days was experimenting with blood magic and something got wildly out of hand. Ghilly? 
The griffons' sheer hatred for the Blight is probably thanks to their being intelligent enough to recognize it for what it is. (Bad juju). Or maybe they're just smarter than the Wardens. 
I also liked how the characters didn't get that much characterization. It felt deliberate. The Blight scoured them and left either functioning automatons and Wardens or dead and broken Wardens. Garahel seemed like one of the only Wardens able to keep his head in the life game, probably thanks in part to a certain Ruby Drakes Captain.
I felt like Isseya berserking up the griffons when she was ordered to was basically her point of no return. She couldn't forgive herself for that.
Also Go-Go Andoral. 
As for the origins of the Blight and World of Thedas:
Whatever World of Thedas says, 'The Claw of Dumat' Codex entry and Corypheus himself strongly point to Old God worship having been on the decline in the years before the Golden City event. It was the motivation for the Seven High Priests to work together to create a crazy ritual to regain contact with the Old Gods.
I love the theory about the Creators being the elvhen pantheon and the Forgotten Ones being the human pantheon. How do the dwarves fit in, or did I miss that? 
I don't think the thread has run out of things to discuss or theorize over.
I think we're just sharpening our swords and preparing for the really out there Leinsky/tin foil hat theories, that are solid structures. (Meanwhile, Madrar adds the finishing touches to her artfully arranged ziggurats.
)