Alan Skorkin writes a paen to the state machine. I've only written state machines for two classes of problems. They are indispensable for scanner-parsers, but I did not do the actual writing: a tool took my grammar and wrote the state machine for me. And for small logic problems I've written trivial state machines around the switch/case statement.
I think Skorkin (and van Bergen, whom he references) overlook the main reason few programmers write state machines: they are hard to reason about which makes them hard to write and hard to test.