Years ago, I wrote and maintained one of the core libraries for Ruby. That experience put me off scripting languages for any serious, persistent work for good. I use them for one-offs, and therefore, I stick to languages that are ubiquitous: bash, awk, sed. Lua isn't everywhere. Neither is Python, or Ruby, or Perl. But bash, awk, and sed are.
Except that, in BB, they're often stripped down so much they're barely functional.
Look, somehow this has become about OpenWRT. That was just a latest example; my post was about BusyBox, and Lua isn't part of BusyBox. I just want developers to consider their deployment environment and maybe generate and include more capable, POSIX BB instead of just choosing the smallest and most useless.