This is my point, other than for use in snow or sand I can't see any good reason for a fatbike. In my opinion it's just another niche cycling market designed for people that lack in the more standard disciplines, the idea of using a fatbike on UK trails is obscene. Why? You would be out paced and out manured by anyone on a 'cross bike, 29er or MTB.
Unrelated but:
Another one of my gripes is the 'beginner training' market,
why do all these videos show people riding 140mm £2000 squishy bikes? If I was a beginner I would look at that video and think 'oh crumbs I'm going to need a bike like that to ride trails like that' not 'actually a hard tail would help improve my technique and ability' in my opinion if a tutorial is aimed at a beginner then the instructor should be riding a beginners bike. Just a thought...
I cant argue for fatty trail riding I havent done it (yet).
http://forums.mtbr.com/fat-bikes/shiggy-rocks-758908.html
On the other issue. I agree. Hardtail for the beginner win.