I’ve been writing Lua off and on for probably close to a decade, and I can’t remember the lack of a round function being an issue. I may have needed it at some point, but it’s not exactly a complicated function to write up in a minute.

To me, the biggest appeal of Lua is actually the lack of an overbearing standard library. It has just enough to be usable as a scripting language within a larger application, and the larger application can always include its own helper library that gets loaded into the interpreter automatically on initialization. Feature-wise, there is enough to define your own OOP helpers (but no language built-in specific OOP stuff beyond metatables basically), there is enough to build your own async/await and generators using coroutines, etc.

Not having a huge built-in standard lib comes with the benefit of not needing to distribute a huge standard lib with your larger application.