These threads do go on and on, don't they?
There isn't "an" answer. There's an answer for every photographer, though. And in my case the answer is yes, MF is worth it.
For me it is like asking if there is a "right" film stock. Of course there isn't. But one could absolutely have one's own favourite film stock. (It was Velvia, since you ask...)
Now, the combination of camera, sensor and RAW processing software forms the equivalent of the film stock. I happen to love the combination of Hasselblad H3D-31ii and Phocus. It gets me 90% of the way to where I want my photos to be and getting the final 10% is a pleasure (I usually run it through Aperture actually, but need Phocus' colour science).
I don't even like the way the shots look with Aperture's default RAW processing- and it is the same data from the same sensor! Sure, with a bit of work you can more or less match Phocus' colour science, but it is much better to start off with something very close to the final effect you want to capture.
Exactly the same way as it was easier to get a film stock that got you 90% of the look you wanted than it was to use subtle filtration and processing and lighting to pull a film stock into colour renditions it didn't really want to go to.
I use a wide variety of cameras and formats for different purposes: four thirds, small chip camcorders, APS-C, full frame. I might even have a film body or two around here still. All have their strengths and weaknesses and I use them for different purposes. My professional work is mostly gorgeous girls and for that the H3Dii- 80 mm lens leaf shutter- Hensel PORTY lithium powerpacks combo is unbeatable for me.
For blow-me-away impact when the pics come up on the screen, NONE of rest come close to the impact of the shots from the Hasselblad in Phocus, with the fine tuning on the day's thousands of shots being a little batch processing to add vignettes etc. in Aperture, plus the retouching. That's why it is worth it: impact and efficient workflow.
Those two things together mean shoots can be artistically satisfying experiences as well as a way to make a living