I'm not suggesting Formlabs would do this, but advertising the $79 add-on and then making very few of them available would be a way for a manufacturer to look open while actually not supporting openness.

The $79 addon is also needed to use all of Formlabs existing engineering grade resins, which are more expensive than the Alpha resins. The engineering grade Tough 1500 is already validated on the Studio 1, and requires the $79 tank, plus is a major selling point of this printer.

There no reason for FormLabs to limit supply of the $79 tanks, it would also limit their ability to sell their more expensive resins to Studio 1 customers, and also removes a clear pathway to get people to upgrade to their more expensive machines, capable of working with their even more complex, and expensive, engineering resins.