Sometimes I run out of disk space. Even having a ton of hard drives, shooting RAW doesn't always make sense. If I'm going to print something, then always RAW. Otherwise, M JPG has worked well in many situations (candids, landscape).
I think M RAW is actually a pretty good compromise, and you're getting noise reduced via interpolation.
Sometimes, I make so many photographs and can get so sidetracked by manual RAW conversion that shooting JPG speeds up my ability to catalog and review everything.
Actually, you can get that noise reduction via interpolation from the full raw, just export as a smaller JPG.
Definitely takes a lot more space, and takes longer to sort through at times because of waiting for LR4 to prepare the preview images on import, even the standard previews. But, for me, that's why I built a 8TB RAIDZ NAS where I keep everything and backup to CrashPlan from that.