Do you think Python isn't popular in academia? I'm not sure I agree--I saw lots of Python written by faculty, TAs and researchers during my MS. Not trying to say it's more popular than R/MATLAB, but I think Python is "sufficiently" popular in academia at this point.
I think this depends very much on what area of academia.
I had heard of R from reading online, but in my time as a physicist I never came across anyone using it. Most of the discussion was around Python vs Matlab, though you also dealt a lot with C vs C++ vs Fortran... :)
