[cmorrisrsg]

The Lua community has been historically more focused on embedded and scripting scenarios, and less on building a comprehensive platform for libraries and applications (compare the quality and availability of LuaRocks to PyPI, Ruby Gems, CPAN, etc.). That combined with the almost non-existent standard library means that not only does Lua not give you a solid base of code to build off of, it's hard to find a community-driven one as well. This leads to developers having to play mix-and-match to get a good base running. Also, the "table can be used to emulate any structure" piece means that every library and developer does OO and modules just a little bit differently, harming reuse across code bases.

There are a couple of syntax decisions (default globals, no ++ or --, indexes start at 1) that might cause negative reactions, but I'd put the lack of libraries and frameworks above that.

Lua is still awesome for simplicity, easy C binding, and performance, but deciding to build a new project in Lua requires a significant investment in just getting the base libraries put together.