[vhhn]

We use embedded R in production in a way some other companies would use Python and I can say having a better compiler would definitely help.

Even if most people use R interactively, having contributers working on compiler has many positive spillovers for the language.

Also note that the R code running behind the scenes of your scripts (powering the functions of your favourite packages) is quite a different language, using less dynamic features. This is where a better compiler would always be appreciated.