I think it is good to explicitly invoke UB. It makes it much more obvious in the code, where it is intended and where not. It's a way to specify that this point in code is never reached, the code can't deal with it and I don't even care what the compiler does in this case.

It's also a good thing to tell the compiler that the programmer intends that this case will never happen, so that the static analyzer can point out ways through the code, where it actually does.