This article has a great overview on the pros to raising miniatures. I don't doubt that the novelty (as in anything) is making things a bit pricey. I'm also not going to bet the farm on them. But I do like the fact that our small family can process one ourself (No way could we do a 900lb steer), they could make it on my small acreage if I do it right, and I could go all organic with them (have an Organic restaurant friend who would be eager to purchase the meat also).
If I wanted milk I would go with a mini for a family, not as much milk, faster to milk, not as hard or dangerous to wrangle, cheaper to feed...
It's not as bad of a fad as say Emu's. If I needed to liquidate I could just sell them for meat, not give them away as pets (maybe he donated those for a write off somehow?). If I don't get into a major registered herd and just focus on meat I think it would work out. Not do all that fancy crud. These are just small cows right?