It wouldn't cost a thing for the AOS to publish their magazine via
Magcloud.
It's probably less about saving money and more about publishing articles that help sell the magazine. In other words...it's a zero sum game. Websites, on the other hand, are not a zero sum game. Not sure why they can't just publish the papers on their website.
Personally, I'm not interested in reading articles on orchid nomenclature/taxonomy. The ecological and biogeographic aspects of orchids are far more more fascinating and applicable to their culture.