Classes are required. Sometimes I just want a c-style program without a class. Java looks a lot like C++ (just with garbage collection, and some more consistently defined behavior). In comparison, golang (and rust) have some nice syntactical differences: inferred types, postfix type annotations, etc.

Go routines are nice when that is all the complexity you want. Having more paradigms isn't an interesting prospect until it becomes specifically useful.

Java may be more usable in many cases, but it, in my experience, just isn't easy to work with.