There have been plenty of "Jowan"'s in DA.
He's just the larva of the corruption of Blood Magic, Next thing you know he would be summoning up some demons because "He dabbled" and thought it was prudent to have access to the assistance because he was otherwise weak.
Jowan's lack of morality, apathy to the suffering his caused and otherwise general smug attitude would have turned him into a mini uldred if not worse.
The Qunari have been beaten back by methods far less corrupting in the past, even for all its supposed might blood magic didn't prevent the Qunari from all but conquering the Imperium during the Qunari Wars. So i wouldn't even advise it used against them unless if it was otherwise called for, but those mages using it would likely need to be summarily executed at the end of hostilities.
With regret obviously; Killing War Hero's isn't something to relish.
Its a school that needs to die out.
Because if the Demons become the only source of that tainted, warping knowledge then there is legitimate reason to kill all those practicing it, they consort with demons.
In re Jowan: You're arguing that Jowan would inevitably have gone as bad as the rest of the Blood Mages? What I think you're missing is that Jowan has a really good incentive to prove you right if you do anything except forcing him to flee... and yet he doesn't.
And I think you're missing the way in which I'm arguing he's weak. I'm not arguing he's a weak mage: there's an argument to be made, but on the other hand he is able to solo that desire demon. Frankly, it makes more sense that the Chantry either sentenced him to Tranquility because he was a known blood mage, or because they thought him weak morally. Which is, in fact, the reason I'm citing him as an example. We know he's of weak enough character to do horrible things. But even he stops short of using the worst Blood Magic has, even if you put him in a position where he's going to die. I think that's stronger evidence than you want to paint it as that Blood Mages won't inevitably go bad.
As for his lack of empathy for those he caused to suffer and general smug attitude, I think you must not have played the same game I did.
In re The Qunari: It worked last time. There is no guarantee the next war won't require blood magic. There's any number of things that could go differently. It is worth noting, for instance, that unless Sten closed his eyes completely he noticed that mages aren't as dangerous as the Qun teaches and don't require quite as much scrutiny. I'm not talking about a Mage Warden, who he considers to be an invalid example of everything.* I'm talking about the unbound mages who quite clearly did not transmit demons by voice. And the Qunari who knows that mages can be given a little more free reign is now maybe the second or third most powerful Qunari politically. **
In re The Last Two Lines: Let's see if I read that correctly. Your argument is that blood mages should be killed to ensure that demons are the only source of blood magic, because that will justify killing blood mages?
In re The New Forum: Is it still possible to break up posts your quoting to respond to individual points, or am I going to have to do this every single time?
* And frankly, Sten's not wrong.
** Oh, crap.