I genuinely enjoy R. I use it for calculations daily. In comparison using Python feels tedious and clunky even though I know it better.
> CRAN had also rerun the tests for all packages that depend on mine, even if they don’t belong to me!
Another way to frame this is these are the customers of your package's API. If you broke them you are required to ship a fix.
I see why this isn't the default (e.g. on GitHub you have no idea how many people depend on you). But the developer experience is much nicer like this. Google, for example, makes this promise with some of their public tools.
Outside the word of professional software developers, R is used by many academics in statistics, economics, social sciences etc. This rule makes it less likely that their research breaks because of some obscure dependency they don't understand.