It seems that in a lot of cases you would be able to iterate faster on the user interaction harness if it's an external harness rather than a full-blown model. For example, if there's a UI standing between the user and the model that needs to change (perhaps by the user customizing it themselves).
IMO flexibility is mandatory because for fixed use cases like live translation or a straight-up voice bot, sure a model like this helps, but in each of those cases you'd just be outcompeted by even more specialized alternatives down the line.