Very interesting read! I needed to sharpen my quest-writing skills and I think this really helps. ;o;
I do like the idea of having gray-area choices that impact the game later on and I think the Witcher handles this quite well (from what I've seen, at least). These types of quests especially tickle my fancy when they blend both good and bad for nearly every option (rather than the lesser of two evils).
My favorite part of the article was probably the statement on writing alone having the capability of making quests great, as opposed to having to have a certain amount of action for each quest. I struggled with this the most because I felt like each quest had to have some sort of "go there, kill this, collect this" approach. It's a relief to not have to follow that. ;_;