As you say, I'm also not entirely sure that recompiling is always necessary, but from experience in my "old days" in the Ubuntu world, an update of R without a recompile of rkward will often break the latter (maybe only for major updates?). On Ubuntu, they had to create a PPA for rkward to follow R own PPA updates directly from CRAN: https://launchpad.net/~rkward-devel/+archive/ubuntu/rkward-stable-cran