Rich and Nathan are really leading the thinking in this area; they are doing great stuff. But you're completely right that it is currently much easier to throw together a side-effect-ful system with frameworks like Rails. That's not surprising: the RDBMS way of thinking has been with us for a long time, and so the tooling and people's understanding of the model has become very good.
The challenge for any new architecture is to create frameworks and tools that are even better (easier to understand and learn, more efficient to work with, easier to maintain, etc) than what is already out there. That's what will determine their adoption, and that's a good thing: we all want good tools to work with, so the bar should be high.
The key though is these abstractions need to be water-tight and as easy to use as their contemporary, side-effecting counterparts. It's just plain easy to rig up a Rails model/controller binary system right now and get things drawing on the screen. It stands clear on the "Easy not Simple" side of things while these new concepts are still very much in the "Simple but not that Easy" side. For these types of architectures to take hold they have to become natural, conventional, and require little extra mental baggage to use them. Fortunately its much easier to make difficult-to-use, simple things easy than complicated, easy things simple. These simple ideas will eventually rise to be easy as well, but as we are in the early wild-west stages of these ideas being turned into systems we are going to see a lot of rapid evolution on the way there.