I think a more ambitious project needs to be undertaken -- an actual middleware product that'll establish standards for connectivity to roasters and controllers, allowing arbitrary pairing of unrelated controllers (DIY or commercial) and roasters (DIY or commercial).
I'm actually serious. Imagine a market where roaster designers didn't have to worry about controller design, and controller designers didn't have to worry about roaster design. Yes, there's a sense in which each needs to worry about the other, but from a standpoint of product design, as long as you stay withing parameters you could be agnostic with respect to the other part.
Dead. Serious. Instead of a 1:1 relationship between controllers and devices, there'd be a many:many possibility space within which the state of the art could evolve.
Who is with me!? We march at dawn!