I really can't understand why I am coming under attack for being involved with a successful "traditional and written in the tradition" style club.

You're not. You're being criticised for what you say here. People* think you're saying that all you need for a successful "traditional and written in the tradition" style club is to let anyone sing who wants to. And people* think that in their experience this kind of open-door policy results in anything but.

*Myself included.