Cons: There aren't that great of CLI tools or REPL's available (mainly to keep the system small). It's standard library is lacking in some parts (by intention to keep it small) compared to other scripting languages. Embedded tech isn't as sexy as frontend tech like javascript/etc. It doesn't come bundled by default with our OS's, unlike perl/python/ruby. The development team is somewhat closed, being a university project from the start.
TL;DR: Lua tries to stay small, and as a result it isn't as much of a multi-tool like other scripting languages.
You'd think Adobe would put more resources into promoting the language.
2) lua has no primary app domain/killer app. games to web to embedded to.. ?
3) lua is happy being itself. dosent try to "be the solution", its just a tool.
As far as marketing goes, I've never seen a company really stick its neck out and brag abput Lisp, but Lisp is somehow still used even today.
lastly, if you think that language designers seriously design languages with the attitude that their language will outdo every other language, I'll begin to question not only your intelligence, but also your credibility and sobriety.