Forget the advanced stats, it also elucidates the best defensive/offensive scheme for the team. That's part of a coach's job description right there. It's probably also not much of a stretch to encroach on the scouts' & GM's territory too - How will our team look if we trade Lopez for Howard? - for example.
When the system gets more optimized and easier to use, the role of a coach & GM could get diminished, and with it, their salaries. Of course they would do everything in their power to stop that.
Except for the coaches who embrace it. When the Mavericks hired Rick Carlisle, a big reason they hired him was that in Indiana he had consistently used his teams best lineups, and in his interviews expressed a strong interest in embracing analytics (which, with Mark Cuban as your owner, you won't ever lack the resources to get the best analytics). In baseball, the best (in terms of wins/resources) team is the Rays, who hired investment bankers as their GM and have a coach who listens to the sabermatricians, platooning like crazy and shifting the infield all over.
When the system gets more optimized and easier to use, the role of a coach & GM could get diminished, and with it, their salaries. Of course they would do everything in their power to stop that.