> ... everyone stumbles across is the "counting from 1" ...
Fair enough :) I find this objection to be largely a matter of taste; it was never an issue for me [added in edit: even when interoperating with C and JS code]. People have made similar complaints about Matlab that I never found persuasive (there are other more persuasive criticisms of Matlab's language design). I think the core argument I'd make here is that if you're using Lua tables in a way that requires array-offset semantics for the index variable, you could probably step up a level of abstraction using ipairs/pairs and save yourself worrying about 1 vs 0.
> The impedance-mismatch becomes even more apparent when the table-abstraction meets serialization.
Lua tables naturally serialize to Lua table syntax (modulo cycles). This is in fact Lua's origin story (if Lua were a spiderman comic, it would be a story of a table description language being bitten by a radioactive register-based VM). At a technical level, how are Lua table literals any less successful a serialization format than JSON (i.e. JS object literals)? To put it another way: JSON doesn't map naturally to XML; should we then conclude that it has an impedance mismatch with respect to serialization?
> doesn't have an established package manager ...
<old guy hat> The idea that a language should have a package manager has always seemed... confusing... to me. C doesn't have a package manager; people still seem to be able to get the relevant packages when they need them through the OS's package manager. That, to me, seems the sane solution. I realize I may be in the minority. </old guy hat>
Having said that I agree that LuaRocks' comparative weakness relative to Ruby's gems limits adoption in mainstream programming applications. OTOH, it is vastly easier to get started embedding Lua in a host program than any of its competitors (this is in fact what drove me to try it in the first place). So it's not all friction on the deployment story.
> ... many of the driving people behind Lua just don't care about it becoming a mainstream language or not.
Yes, I think this is likely true. I don't think any of the core contributors care about it being "the next Python/Ruby/Perl". If I had to summarize the emergent aesthetic, it's that Lua is designed to be a just a language with a large set of DIY practices around it, rather than a curated software ecosystem.