Well, I'm still young and don't plan to stop using film. There should be a way to manage risks like you said and still provide convenience of buying a ready-to-use mix. For example, I understand taht Crawley publishes the formula for discontinued Paterson products that he designed.
Finally, providing the formulas adds to the comfort level. With manufacturers closing up shop and dropping products left and right, knowing that a formula (or even just a close cousin to it) is available online means that investing in learning the subtleties of a new product won't be in vain, even if the product disappears from the market.