Anti-intellectualism is nothing new, especially among lower level ESL teachers in Thailand, yet there are many legitimate criticisms of “academia” in every field.
I would suggest using empirical evidence or experience and common sense is not an either/or type of situation, but use of both is often optimal. Experience can be a great teacher, but it is obviously limited to the little world we have personally experienced. It is also limited due to a variety of observation and analysis biases each one of us has. Reading books, journals or attending courses allow us to learn about far more of the world than the specific situations from our own specific perspective. While there is a whole bunch of BS and poorly designed research published in academia, good academic work tends to let us explore nuances and complexities that can be useful.
For example, let us say you find technique 1 works in your classroom while technique 2 does not. It is likely you will think technique 1 is good and technique 2 is bad and will use this information in your career. Technique 1 worked well in your classroom, but it might be because it fit the context you were teaching in and might not fit a different context. If you learn the theories behind the techniques you might be able to determine in which situations technique 1 is likely to be successful while technique 2 is not. But you might also see technique 2 is not necessarily “bad” but could work well in a different context.
Learning a foreign language is difficult, and something few NES English teachers have actually done. All academic research is limited and you will not find simple answers to complex questions in a single article. If you are serious about having a teaching career, I would suggest you get as much education and experience in your field as possible.
While we can find exceptions, the empirical/academic studies indicate in almost every profession salary and income are strongly and positively related to higher levels of education and experience, indicating the market tends to reward us for both. Go ahead and argue against the market if you like, but I don’t like your chances. I don’t think taking a course or reading some academic journals articles will make you a “good” teacher, but I seriously doubt it will make you a worse teacher.