I first mention that JS has been actually successful in non-glue areas :) Dynamic languages are hard to scale, but it is possible after some headaches.
The lack of quality library also means that you are even more risky when you are writing a small program (because you have less incentive to write it yourself). I have experienced multiple times that even the existing libraries (including the standard ones) had crucial flaws and no one seems to be bothered to fix that. Also in the embedded setting the use of snippets, rather than proper libraries, are more common as libraries can be harder to integrate, and unfortunately we are left with PHP-esque lua-users.org for Lua...
The lack of quality library also means that you are even more risky when you are writing a small program (because you have less incentive to write it yourself). I have experienced multiple times that even the existing libraries (including the standard ones) had crucial flaws and no one seems to be bothered to fix that. Also in the embedded setting the use of snippets, rather than proper libraries, are more common as libraries can be harder to integrate, and unfortunately we are left with PHP-esque lua-users.org for Lua...