I was on a jury in 2006 for a domestic abuse case. They intervewed the jurors, dismissed one I think, and then accepted that replacement. The selection took about an hour. For this Tsarnaev case they interviewed 256 people which is insane. At that rate I would guess you get both bogged down by the sheer number of people, but also by the minutiae of each persons differences thus leaving a larger hole of subject matter for the other side to fit an appeal into. I think peer selection still has a place in the process but it sounds like in this case they were doomed from the start.
I've been through the process once. They dismissed one guy because he said he'd never vote to convict anyone of anything because he police are corrupt. The judge was like, "You're lying." And he remained steadfast, so they had no choice but to dump him. The defense dropped a person, too, because she had a cop for a husband or something. In general I don't think voir dir proceeds line the process described in this article.