I still think it is great. People who never learned about UML tend to reinvent some such thing when they wish to communicate the same structures and information.
Then you end up with 10 different people drawing approximately the same information in 10 different forms, and all will require some level of explanation of notation and grammar for others to grok it.
A class diagram can contain a lot of rather valuable information.
I do agree that sequence diagrams are great, but if you rip them out of context and throw the rest in the bin it can only partially communicate, whereas if you had the object model to study as well as the sequence diagrams new connections can be quickly made.
To this day I prefer to create my object structures in a UML diagram. Plenty of software takes it creates the code, or takes the code and produces the diagram.
I love creating the diagram(s) when I first start working on an existing system.
What I have seen of code generation off of sequence diagrams have bit hit or miss. more miss. But reverse engineering sequence diagrams can be quite revealing.