The issues I see with miniaturizing breeds is the health problems that can and do occur. One thing I'm noticing with North American miniature Aussies is that their heads are getting smaller but their eyes are staying the same size. I talked to a friend who has two mini Aussies, and he says the breed is also starting to develop many internal problems, because the bodies are getting smaller but the organs are staying the same size. I don't know much about these issues as my breed is not currently in danger of being miniaturized -- though I do prefer my Belgians smaller! Honestly it sounds silly, but I've seen it happen.

I have no issues with the breed itself -- it has it's own parent club, it's being considered for registration by some of the bigger kennel clubs, and it has been bred for a long time. There aren't any smaller breeds being mixed in (unlike "toy" or "teacup" aussies). I don't see alot of consistency in the looks of these dogs which tells me that they are bred more for working ability and temperament -- a good thing as opposed to most Aussie breeders who focus too much on looks. I've recommended the mini aussie to people who want an aussie but want something smaller and less time-consuming to groom.
However, I do not agree that any breed should simply be miniaturized because it's size is not preferred. Every breed has it's ups and downs. If something is impossible to live with, get a breed that has a downside you CAN live with. There are plenty of things I can't stand about Belgians -- but the downsides I dislike are all in temperament, something I can try to breed out without completely altering it's physical appearance and turning it into a "new breed."