[bathat]

Sure, but, unless you're a rockstar graduate student, you do R in service of your advisor's grant needs. Unless you're a rockstar post-doc, you do R in service of your PI's grant needs. Unless you're a rockstar PI, you do R in service of your own grant needs. Wherever you end up, someone is writing the checks. That someone gets to determine what you research.

I'd guess that computer science is very different from experimental physical science disciplines: In experimental, you have to have a research advisor with grant money if you want to have vacuum pumps/oscilloscopes/glassware/liquid nitrogen/etc., even if you plan to TA your way through grad school.