Lisa,
I think they've done it that way for years ... it's all about the money, honey! They COULD put up a prelim schedule online at least ...
I live SW of Houston, I haven't taken any classes in recent years but I certainly GO every year! Wouldn't miss it! We usually go 2-3 days and still don't see it all ...
They have a variety of lectures and fun class demos on the show floor ... you just need to schedule those into your day's shopping, a good way to rest your feet!