I'd be inclined to leave it up to the discretion of individual organisers as to what they feel is appropriate for the individual sessions or festivals they run (I'm certain Richard will do his own bit, in the session he runs.) As soon as people feel they are being pressured to 'sign up' there will be automatic reaction against that pressure, and that won't be positive for the cause in any way. Better to tread gently with contentious issues I think, in order to prevent rejection of the whole issue. This doesn't prevent individuals 'flying their own flags' so to speak. Or indeed arranging an informal discussion amongst those already on board, and possible interested others.