I have no doubt that there would be those trying to make technologies that negate the need for magic, and I’m sure that many would see success in such endeavors. However, I think that regardless of they invent, someone else will then come along and make the same thing, but further enhanced with magic in some novel fashion. In my mind, magic isn’t inherently special, it’s just another set of technologies that, like any other, allow the leveraging properties of the natural world to accomplish a task more efficiently.

Secondly, the roles of production and R&D would be separate only if the scale of production is large enough. I’m thinking this would start at the local blacksmith level, where working the forge and creating new alloys may absolutely be done by the same person (or team) who is passionate about their craft. If the world jumped directly from that era to the factory era overnight, you’re absolutely correct that the evolution of a wizard from worker to researcher doesn’t make much sense. But, that’s not how society evolves—it’s a gradual process. And I think that in an environment of gradual evolution, those that understand the most fundamental secrets of the craft on an intuitive level from the beginning often end up being near the top of the food chain in the end.

I think perhaps also the scale I have in mind is just smaller than what you’re imagining, which could lead to our differing views. Neither is more or less correct I don’t think. 🙃