Well, first off, breeders aren't in the business of educating the general public. The breeder's business is breeding and selling snakes. All the breeders I know are perfectly willing to share their knowledge, but that's not the primary mission. It is useful and beneficial to educate your customers as to the care and husbandry of the animals you are selling them, and if you have a chance to educate some of the general public regarding some aspect of reptiles or their captive care, that's also beneficial to all herpers, as well as the animals.
We also aren't running zoos. There is a LOT of work involved with breeding reptiles, and if you have to spend a couple of hours a day showing snakes to somebody, that cuts into your time for the work you have to do and your time with your family. Feeding, cleaning cages, keeping records, shipping snakes, preparing for shows, ordering supplies, dealing with medical issues, preparing cages, etc. is a full time job. Most breeders sell the bulk of their animals at shows, or over the internet. Since the business is geared that way, it is very difficult to make time for walk-in visitors. Pet stores are set up for that sort of business. You can't just let people roam around while you do your work, either. Believe me, people have more nerve than you would expect, and will open cages and remove animals without even asking permission.
There is also the problem of visitors possibly introducing diseases into your collection. People invariably want to handle the specimens and can easily vector bugs, especially if they have previously been to other establishments that day, or working with their own animals.
Plus, there is a security issue involved. You don't personally know the people that want to visit, usually. There is always a possibility that you can pack up and go to a show only to return to discover a break-in and your breeders gone.
It's nothing personal if a breeder refuses on-premises visits or asks for you to make an appointment. He's only managing his time and protecting his business.