If the vision of the movie or character calls for an R rating then by all means, go for the R. Making movies R rated just because is stupid though. I'm not saying that's what's going on with Wolverine, but it sure is convenient timing.
Terminator would have sucked as PG-13. The Dark Knight would have benefited zero with some blood and an R rating.
That's why I didn't even consider seeing the new one. Can't make that crap PG-13. Thought they'd know better than that.