The reason these dependencies were commented out is kind of complicated. See https://spack.readthedocs.io/en/latest/build_systems/rpackage.html#recommended-packages for the reasoning. The problem is that R by default comes with a set of recommended packages. If Spack installs these packages alongside R, and they are also listed as dependencies of an RPackage, Spack won't be able to activate that extension. I know the docs say that we add a --without-recommended-packages flag, but this isn't actually true, it was wishful thinking on my part. At some point, someone needs to add this flag to the r package and ensure that every other RPackage explicitly lists its recommended dependencies, like you're doing here. Anyway, I'm in favor of this change as I think it's a step in the right direction.