In my experience (a teacher coming from a family of teachers), one reason why teachers may be reluctant to adopt new teaching methodologies is simply "too much work, too little time." There are so many hours in a day, and so many dollars in the pocket. Even those who wholeheartedly embrace a new methodology often have to phase it in gradually in order to keep the considerable preparation time (for all-new lesson plans and handouts) and budgetary strain (for new classroom equipment and materials) manageable. There is also a considerable professional risk to piloting a new methodology, especially solo. Teachers have to keep parents' opinions and "evaluation time" in mind. It is no surprise that many teachers opt for the safer, easier status quo.