Always weird to meet Emacs people who don't like having to customise Emacs. That said, ESS has some weird defaults, not sure I'd lay them at R's door tbh.
ESS defaults predated Hadley's contributions by a decade, making his seemingly unique adoption of snake case extremely unsociable. I actually use _ to <- a lot. It's enough of a pain in the ass, I basically stopped using his packages. This was annoying, but ultimately the Hadleyverse became a bridge too far for the kind of bread and butter data science I do, so it turned out to be helpful to me personally.