Sometimes, in my darker moments, I have the terrifying thought that one of the reasons that many users like R and made it popular (apart from the historical context of its now many libraries and being the main free version of statistical software), is specifically that it isn't robust and sensibly designed from a programming/analytical perspective. You can download a package, type in a preset command on a preset thin…
I think your fears are misplaced. R users love R because of ease of use. R does sometimes ignores ugly corner cases in favor of that ease of use (though I'm skeptical this damages the validity of the answer in anything like 5% of cases), but that's a side effect. sklearn and pandas are great, but you still simply have to be a programmer to use them, or at least much closer to a programmer than many statisticians want…
Free. Quick. Interactive. 4 lines. Done. What's the value proposition of Julia compared to that? Now you can argue that Julia will allow better type specification and specialisation, etc, etc. But that's not what's valued or used in your example.
Now, my mindset/domain has to engage with such, and i freak out at the implicit-ness/assumptions inherent in such code, especially with some of R's additional design choices.
In my mind, having code that crashes/errors out when something ambiguous/dangerous is encountered in your example a "good thing". But that's not what's valued in the above example.
And while Julia would allow someone to program in such a way as to specialise or raise these errors and concerns, what is valued is the ability to not think about them. And if you don't think about them, or even as a library designer, if you want to program in such a way that your user primarily doesn't want to think about them, then you're effectively very close to reinventing/reimplementing a new "R", with all its costs and benefits.
I'm just making this observation explicit, even though I actually do value the things the Julia crowd seems to value, but I'm not sure I'm in the majority, and I'm not sure you can push that down into the libraries without exposing concerns most users don't want to be exposed to.