Lua's a little more opaque than Python or JS, a little more flexible, a little more bug-prone, and a lot simpler. But those aren't the reasons VLC and Wireshark and WoW use Lua instead of Python or JS; they use it because it's enormously less costly to embed. Imagine you decide to switch from Lua to Python for your game. Now you have:
- 3600 kilobytes of bloat instead of 110;
- a huge and bug-prone ABI to deal with to make sure Python doesn't inject memory leaks;
- Python assholes publicly shaming you for using an unfashionable version of Python.