It's a bit of an unkind example as most would write the latter as

    if (obj instanceof Point p) {
        System.out.println(p.x()+p.y());
    }

But I can maybe see the value if you need to use x/y more than once.

However in Java it's common to have getX() style accessors, for which this syntax doesn't seem that helpful as your variable would end up being called getX