I imagine things will be further shaken up when it will be incumbent on any organisation be they 'clubs' or 'schools' offering flight training courses to become an ATO. However, I think it is prudent to collect the details of anyone flying in a 'club aircraft' (be they students on a course or trial lesson/gift voucher flights) and a membership procedure is an efficient way of collecting these details. Although yes, some organisations charge extra for the privilege of writing down your contact details!
4B