I haven't read any of the novels but I've read summaries of "The Stolen Throne" and "The Calling" (avoiding "Asunder" spoilers, a bit, because I think I'm more likely to read it). And I do understand that it gives more texture and depth to Loghain's actions, and makes him more sympathetic, as he becomes more sympathetic if you add him to your party and get to know him a bit. But I don't think knowing the reasons for his actions really excuses them, especially not the more heinous bits like selling elves to slavers.

I'm also curious to see your thoughts on Meredith after you've met her, and during a second playthrough. I actually found her more interesting the second time around, in terms of being a shadow figure.