You're right I might be conflating the comparison but does it matter? JavaScript is a dynamic language which allows strict access controls (although its semi-hacky to do it).
Also, when is access control by convention a good idea? Sure you can live with it as Python and Ruby devs like myself do, but compared to languages which give you stricter controls like Erlang (which is also dynamic) its pretty obviously worse when it comes to building large software systems because it weakens the guarantees you can make about your libraries and the libraries you use to build those libraries.
"People seem to be able to build large systems in both languages fairly effectively."
People can and have built large systems in assembly. That doesn't mean assembly provides the optimal means for building composable software. Why settle for something thats mediocre when you're still unstable and change it for the better?
Well, I'd be all for making Base as small as possible since I'm not big on monolithic standard libs and think everything possible should more or less be a package which you can include on a per project level.
As for the semantics and mechanics, I'd like to have the ability to have true public/private like rust or go, so that you can have a tightly defined public api and be sure your users only have access to that. Also I'd like to see the whole thing simplified it is way more complex than it needs to be. Just have import act like a function for example it could take a module, a keyword, and a vector like this:
compare the above to https://docs.julialang.org/en/stable/manual/modules/ as far as I can tell the functionality is the same. Anyway those were some of the things that I didn't like about it and would have changed.