UML Statecharts are definitely an interesting model , being HFSMs, and thus modular/extensible. But I think there is a lot to be said about context and application - this kind of thing needs to have a revolutionary 'right place, right time' opportunity.
Kind of like Hypertext and Hypermedia, which languished as an academic pipe dream for decades with occasional commercial moments of brilliance (Hypercard), until Tim Berners Lee figured out the right mix.
i have a project dating back around maybe ten or 15 years that could read the text format (xml iirc) of dia drawings and execute them.
the main problems included being actually very hard to understand visually, very ugly, and subject to all sorts of edge case errors when running. basically easier to write code then compile uml from that for anyone crazy enough to want it.
the crux of the problems is verbosity. Once systems start to get to a reasonable level of complexity the uml diagrams can cover the walls of a large room.
Kind of like Hypertext and Hypermedia, which languished as an academic pipe dream for decades with occasional commercial moments of brilliance (Hypercard), until Tim Berners Lee figured out the right mix.