State machines have been the bread and butter of embedded systems for a long long time. Many years ago we used statecharts as a basis for a machine controller for a complex machine and the result was extremely robust. It's very hard to forget to handle something when you're working with this model. The downside though was that didn't have code generation tooling and whenever we wanted to make a change we had to change the visual statechart and then go to the code and make the changes there which was a bit of a pain. If you have the right tooling though that becomes a lot easier.

Because state machines are a weaker computational model they are easier to reason about, you can prove things on state machines you can't prove on a general program, you can do things like state minimization etc.