We specifically intend for the 4.0 raids to be puggable now that Firelands is out. Grabbing some tier 11 by way of Justice, quest rewards, plus across the board difficulty nerfs should really be enough to get them going.
The patch has only been out a day or so though. I think it'll probably take a little bit before people really get it into their heads that they should be pugging the previous tier because it's not too hard to be successful. It's just getting people used to the various encounters and mechanics.
Maybe people are waiting for the holiday weekend? If nothing else, leading one yourself is always an option. I think we'd agree that we need some better ways to get pug raids together considering we intend to follow the "New Raid is Hard, old Tier is Puggable" format from here on.