IMO I think blood mages should think about themselves before others. Since it is about using blood in place of lyrium it's a tremendous boost to your power. If like in previous games, the blood magic animation is portrayed as the blood mage using his own blood I wouldn't like it.
Why would a selfish blood mage use his own energy to attack an opponent? Better to use the blood of another than your own, stab your friends' stomach, summon a tremendous snowstorm and run away from the templars.
Just a visual example of how I see blood magic and the people who would choose power in this way. Of course if you just like learning things that doesn't make you a blood mage, you can read all the books in the world about all the different types of magic just for knowledges' sake.
But a blood mage fighting with blood magic should be selfish imo.
A blood mage isn't necessarily selfish. If he or she chooses to use his/her own blood, that's a choice, same as it was the choice of the Tevinter to sacrifice slaves.
I do think there should be more repercussions to being a blood mage, but they should be more social and based on in-game choices. For instance, you could choose to sacrifice someone for your magic at some point, if you were a blood mage, or you could be honorable and choose not to. But, it's already pretty disturbing to slice yourself open all the time for the sake of spellcasting. You know nothing good can come of that.
While blood magic is inherently not good to mess with, that doesn't mean that everyone who uses it is necessarily a selfish person. And a blood mage makes as much sense as anyone else as a spirit healer, and perhaps more due to their already demonstrated willingness to deal with spirits/demons.