Directors don't generally join organizations to commit misfeasance. They join in good faith, trying to do their best, as we all know. Really, the question at a macro level is about how you get the best directors, the best governance, of the not-for-profit sector, and that is to develop the biggest pool of potential directors and officers. You do that by removing some of their fears and some of their concerns--legitimate concerns--about unlimited personal liability for doing a volunteer role.
This immunity from liability was recommended by the Panel on Accountability and Governance in the Voluntary Sector, under the Honourable Ed Broadbent, in 1999. That was based on extensive consultations across Canada on the feeling about and what people really thought in regard to that delicate balance, which, as you quite rightly say, is an open question. But people who have looked at this question have also felt that, on balance, this would be a positive thing.