"If trees could scream, would we be so cavalier about cutting them down? We might, if they screamed all the time, for no good reason."
-- Jack Handy
If you want votes to mean something, you don't want people just tossing giving them out for the heck of it. "Oooh, this question mentions R - I've heard of that, UPVOTE!!"
Ever notice how some of the most up-voted questions and answers on SO are also the most useless? Favorite lists, GTKY questions, etc. - stuff that readers don't have to think about, but up-vote purely because they identify something familiar. The other extreme are questions and answers that only a handful of people in the world could ever understand or appreciate. If you want meaningful votes, you have to look for something that falls between these.
R seems to be on the low end of the spectrum, but hardly at the extreme edge. Questions and answers do get some attention. They may not generate the same kind of rep that, say, C# Q&A does, but then... nothing does.
If you feel R Q&A needs more votes, go vote. You have enough votes to burn to make a sizable difference, if you really care enough to do so. Whether that's for the better or not depends largely on how much care you put into it...