I think tradition had a lot to do with the success of those weekends in the past. For years, the CASCAR Super Series opened and closed their race season on the May and September long weekends, so people would come to the May race to see who was new, etc., and to the September race because it was often for the points title. They had a pretty healthy following then, and I can remember the turns 1 and 4 areas on top of the hill being lined with sponsor tents.
Those days are gone, however, but hopefully they'll be able to find something in the future to hold and build upon on those weekends.
Radical change will always bring radical results, however sometimes those results aren't the ones anticipated
Seems like Victoria Day weekend weather is often terrible...this year being the exception of course.