Looks like a lack of good links can also play into this as the counterbalance. What do you think?
I'd agree with that. A few sites I monitor that have been doing well and don't do link building (let it happen naturally) have all lost significant amounts of traffic with this update.
I wonder if they've given good links more power as opposed to punishing bad links (or perhaps a bit of both). So sites with weaker backlink profiles could have lost out without actually doing anything wrong.