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Q: Can I use C++'s syntax for ostreams: cout << x << y ... ?

You can. If you don't like writing ``print x, y'' then you can try this:
import sys

class ostream:
    def __init__(self, file):
        self.file = file
       
    def __lshift__(self, obj):
        self.file.write(str(obj));
        return self

cout = ostream(sys.stdout)
cerr = ostream(sys.stderr)
nl = '\n'

cout << x << " " << y << nl

This gives you a different syntax, but it doesn't give you a new convention for printing--it just packages up the str convention that already exists in Python. This is similar to the toString() convention in Java. C++ has a very different convention: instead of a canonical way to convert an object to a string, there is a canonical way to print an object to a stream (well, semi-canonical---a lot of C++ code still uses printf). The stream approach is more complicated, but it does have the advantage that if you need to print a really huge object you needn't create a really huge temporary string to do it.

The most simple solution to this concern is to have Java deprecate use of the + as String concatenation, forcing the programmer to accept that Strings are immutable.  This will probably not happen in practice for reasons cited as "convenience" and backwards compatibility.