Because Lua is not openly developed, "proposals" should be rare. When we feel compelled to offer one, we should seek alternatives, such as an example of something you are trying to do that is hard to get done in Lua (maybe why you are using Lua to solve this problem) and the value of a solution. (what your life would look like if it were easier)
Narrative:
If you are inclined to spark a conversation about "what would be cool," then you can expect a debate about a theoretical universe that does not exist, probably led by an opposing point of view. Those can be fun, sometimes; like arguing about rock and roll and whether or not Rush should be in the Hall of Fame.
They are not fun when we believe that the outcome of these fantasies have weight. Then we defend them and display all of the behavior that is so easy to fall into when we argue, made worse by the fact that we are not sitting next to each other, IRL.
Perhaps worse, there is the chance that a good idea might be in that conversation, and those conversations are probably the least effective way to actually influence change.
Think of your experience as a developer. When you are making software for someone else, to solve their problem or to make them money or because you're altruistic, nothing is more frustrating than to have them ask for a feature, or worse, for an implementation detail. You want the freedom to do your best work and having constraints put on the *way* that you do it, or even a conversation about how you should do your job, is deflating. It assumes that your are a worker-bee, devoid of sufficient creativity.
On the other hand, context and feedback are food. If you're like me, you want a normative explanation (a story) of the opportunity and a sense of the context in which it is to be integrated. You want to know the value of the opportunity and you want to know how it fits into the mission of the project. That can be inspiring. With that, you can help.
Few of us are going to have a unique and valuable insight into features that should be in Lua or changes that should be made, especially since our vision of it is personal and Lua is not ours. [unless we fork it, which we are often reminded that we are free to do: LuaJIT, MoonScipt, etc]
What we *do* have is an excellent insight into our own experience. If we can tell that story, then we are truly adding to the conversation. That story can even include ways that you're working around a design choice in Lua or a request for ideas or a hack.
As a recovering Proposal Factory, these are some things I think before setting down to write about a change to Lua:
* I ask "Why is this so?" Nobody can argue against a question. I'm often delusional about my ability to come up with awesome questions, but I've come to expect a good answer that will change my mind and that is always valuable to me, personally