There are a couple of reasons I think - first, the location of the sale was moved one week before the sale to a location about an hour from the original site. I think that maybe pushed some people from not attending. The second is, historically, the sale often has REALLY bad weather.
I do agree that the market seems low, but I must add that many of the people that attended the sale were NOT concerned about pedigree, etc... but bought cute, short and colorful horses. I think that there will always be a market for good quality horses - I've sold many horses for competitive prices this year.