While I was enrolled as an engineer, one math professor decided he didn't like the textbook being used to teach the course. It was wordy, confusing, and generally not well-written. So, he embarked to write his own book that would be much easier to utilize while teaching calculus courses. He wrote up all of his lecture notes in textbook-like form for easy compilation later, and passed them out to his students for free with each lecture. His notes were very easy to comprehend and matched up with his classes very well. Everyone enjoyed having him as a professor because he actually cared that his students understood the material better.
In his case, sure there was some future financial gain in it for him. (After he found a way to get everything published.) But, it was more about his ability to teach the students effectively. Other professors didn't care that he used his own teaching method or didn't use the standard textbook for his courses. And we all turned out just fine because he still taught all of the material, just in his own way.
BR I guess my point is this: let the teachers choose their own methods, as long as they teach the students the required material. Oftentimes, this can result in greater effectiveness, as it's more comfortable for the person doing the teaching. And that, in turn, usually translates into better learning of the material by the persons being taught. Don't just railroad everyone into doing the same thing. That's how we get all of this common core and standardized testing BS that doesn't really do anything for the teachers or the students.