I think autogenerating UML from existing code to get an overview over e.g. your database schema, state machine or class hierarchy is fine. Hand-drawn UML is use

I think autogenerating UML from existing code to get an overview over e.g. your database schema, state machine or class hierarchy is fine. Hand-drawn UML is useless busywork, it is usually faster and quicker to just write the code. Also, autogenerated UML doesn't go stale as easily, since you can just automatically recreate it. And I agree, the most useful diagram type is a sequence diagram. The rest is often useless because OOP has declined, weird arrow types are unintuitive, language features do not always correspond to UML features and UML tooling doesn't fit very well into common software development methods. E.g. you cannot 'git diff' UML diagrams; while it would be theoretically possible (git diff can take helpers), no software implements this, that I know of. Overall, about UML's decline, good riddance. Throwing boxes and arrows at a whiteboard occasionally (without tons of formal semantics) is all anyone needs.