First, I know that on windows you can compile packages from source using Rtools. We are trying to avoid having to compile the packages locally.
Are the Windows binaries not being compiled for older versions of R? See screen shot below. Or are they only being compiled 1x a year or 2x a year? Updating to a newer version of R is not possible right now.
I am not familiar with the binary/windows/R packages process to know why this is happening. I know that volunteer(s) maintain this windows binary compilation and it happens automatically.