I was thinking the same thing, but from what I can tell there seems to be significantly more opportunities for a web-dev rather than someone that specializes in R. Or I might just be looking in the wrong places...
Here's the thing: Only you can do the the R jobs, all the web developers can do the webdev stuff.
I'm sure you're awesome. Don't sell your self short and chase webdev jobs that I can pay someone over seas 15k a year to do. Focus on the R stuff, but you're going to have to push a little hard and find a better fit.
When every key fits a lock the key isn't worth much. When you're one of the few keys that fit the lock, you're worth a lot to the right lock owner.