Perhaps you have a problem with the way the instructor gives feedback, not his "teaching Method" per se. OSensei told us to always practice in a joyful manner. It seems that the feedback your instructor gives is not creating the type of environment where people can enjoy their practice. People become frustrated and may ultimately leave. If what you have posted is true and not just your own perceptions, here is one of many options: Join together with other people in your dojo and approach the instructor with some feedback of your own. You would actually be giving him feedback on the manner in which he gives feedback to the students
. If you can give him positive feedback, maybe he will be more willing to give positive feedback during instruction. This can be as simple as saying, "we LOVE when you say positive things about our practice, please do more of that." IMHO, this simple little communication could make practice more enjoyable. I'm sure people will post other options as well. Good luck.