I can see why you would say that, especially back when we initially started looking at it (before Yehuda went over to Strobe), but more recently the docs/tutorials have become much better. We have invested a decent amount of time learning the framework and it has become really productive for us. Also, I haven't seen anyone using statecharts with the other frameworks. Not that they aren't, just haven't seen it. If you don't really know what statecharts are or what it means to have one backing your application, I would recommend just looking into it. It was eye-opening (for me at least).
Another great post Luc. It's really been bumming me out that more people aren't talking about statecharts and web app development (especially with Sproutcore). After developing web apps for over a decade, watching Erich Ocean's course on statecharts with Sproutcore was a eureka moment for me. It was like, "Finally, a sane, testable, non-hacky-feeling way to build responsive web front-ends!"