As a guy also trying to make a living at this, I want to add a bit to something Guy mentions, as different tools have very different uses and provide solutions others cannot. I shoot a lot of action sports event stuff, and my client base has the bucks to spend on gear. I constantly see them showing up to events with gear that matches mine (Canon 1-series and "L" glass) for the same type of work. Some of these folks will even stand right next to me taking their own shots. In the end, they still wind up buying from me, because they see that my work is much better than theirs...probably because I "practice" about 4,000 frames per week during peak shooting.
What is more scary is having these same clients wanting to use some of my shots in ways that I have not always intended. This multi-purposing of image use is not a problem for smaller format, if the uses are small placements, but it makes a huge difference when they suddenly decide a double-page spread or a poster is how they would rather use the image, or even larger than that. While I may be able to push my FF 35mm files pretty far, there are some significant limitations once you start to need larger printing sizes. If all of the work is small Web-sized, or spot ads, then MF is overkill, in most respects. That is not the way things are heading from what I am seeing. Clients are wanting and now expecting much higher quality images that can be used in a variety of ways, some going well beyond what may have been considered at the start.
Like Guy, I used to shoot MF film back in the day. It was able to deliver things far beyond 35mm film then, just as MFD does today over DSLRs. Is it needed ALL the time? Absolutely not. But if your reputation is riding on the image quality you deliver, it can make a huger difference. I am about to plunge back into MF myself, expressly for the reasons suggested above....to meet both my image quality demands, and those increasing demands/expectations of my clients. There are things that MF will be unable to do in my shooting, and I will keep my DSLRs for that, but there are other areas where it far exceeds what one could realistically do otherwise. Not all shots can be done using 35mm and stitching, so a great MF file will make the day in those cases.
Have to completely agree with Irakly again on this....these are tools for some of us, and they can and do return their cost many times over. They do depreciate, from my accountant's perspective, and that is a good thing, but their capability does not depreciate in the same way, and that is a better thing in my perspective.
If one does not need them, do not bother. If one has the need and/or the means, they bring another level to the imagery that DSLRs cannot in many ways. MF is not just about "studio", unless one thinks about their "studio" as being everywhere and anytime ;-)
LJ
P.S. I wanted to add that I think it absolutely fantastic that there are so many dealers, reps and others from the various gear providers participating here, as they are able to bring a good value/use perspective that is much broader than any one or several users alone. And none that participate on this forum have ever been "pushy salesmen", but instead offer rather candid perspectives hard to find elsewhere.