[pron]

In Java, unsigned arithmetic is available through an API and, as you said, it is pretty much only needed when marshalling to certain wire protocols or for FFI. Built-in unsigned types are useful primarily for bitfields or similar tiny types with up to 6 bits or so.

[pjmlp]

I miss them for doing bit juggling like file headers or networking packets.

However I do concede writing a few helper methods isn't that much of a burden.

[pron]

I think all the unsigned arithmetic you need is already offered. Unsigned shift right is an operator; the primitive wrappers offer compareUnsigned, divideUnsigned, and remainderUnsigned, as well as conversion methods; unsigned exponentiation is offered in Math (because signed types in Java wrap, there's no need for special unsigned addition/subtraction).