On one hand, if a person owns the stallion and mare and wants to breed, then it is really their choice.......
But I think the real question is what will SELL in this economy and some minis ARE selling quite well. Quality seems to sell. If you have a foal that will be able to compete at the World/National level, then I think it will sell. This of course would start with conformation, but not end there. Movement, athletic ability, and personality (not quite the same as attitude but related) will help too. There needs to be something that sets the horse apart from all the other foals or minis out there. (Color, charm, blue eyes, training??). In our area, driving horses seem to be selling well and if you read the Driving Forum on here, I think this is a trend to continue. We decided to breed two mares for next year with the hope of producing some nice 33-34" future driving minis with incredible movement and wonderful temperament and personality. If we get another one just like the colt we got this year we will be happy and we hope so will the people who keep inquiring about him! (He is a keeper).
I am sure there are other characteristics that will sell, but I think breeders have to put more thought and energy into marketing than in the past.