Well, my opinion is that you give the power to the user. It's up to them how to use it. Obviously, this wouldn't be the default action. A shoot for one of my clients three years ago currently takes up 1/2 a terabyte. My obligation to store the images ended a year ago, so, it's time to recycle that space. Rather than just deleting all of the RAW files, it might be prudent for me to hold onto the JPGs for another year or two before deleting them too. I had the same situation with a 100 gig of family snapshots. They're snapshots. I don't need to keep the RAW files around. Anyway, a simple checkbox would be all that's necessary to save a few steps.