Seeing the discussion here, I'm feeling that the good parts of UML has not found favour with many people: the Harel Statecharts, they were semantically rich and

Seeing the discussion here, I'm feeling that the good parts of UML has not found favour with many people: the Harel Statecharts, they were semantically rich and could easily describe complex behaviour. Infact they are better than Sequence diagrams to specify which sequences are legal and which are not valid. I don't see any post-UML method that provides the same expressivity as Statecharts for that purpose.