Any language can be cross-platform with a little more work. If I remember correctly, any OS can run python stuff so long as it has an interpreter installed. C++ can also be cross-platform, I'm sure, as a lot of games on steam are made with C++. Perhaps more systems would have Java installed over systems having C++ redist, but it's not hard to have something install the required C++ redist on first run. Everything has its ups and downs, but as Key Gear has fought with me before, Java takes a lot more work to get something done than, say, Python or another scripting language would take.