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I agree with that and I use final as much as possible. E.g. instance variables that don't need to change, I almost religiously declare them as "final" and initialize them in the constructor.

What I mean is that what Java really "should" have is const like C++. A C++ function with a prototype of:

    int doSomething(std::vector<int> const &x)

tells me much more than the equivalent Java:

    int doSomething(final List<Integer> x)

Also C++ member functions can declare themselves as not modifying their "this" instance. E.g. there's no way to write this code in Java:

   int X::doSomething(std::vector<int> const &x) const {
       ...
   }

which is an extremely powerful, compile-time checkable description of what we are doing.

It's not that final is useless (probably wrong choice of words there), what it does is okay and it's correct to use it as much as possible, but it's a far cry from the static guarantees afforded by const-correct code.

I also agree that the correct approach is immutability by default, but that ship has sailed, and it's also an orthogonal concern to what I'm saying here.