These measures were designed consistent with the other non-refundable personal income tax credits in the act to be non-refundable. It would be a departure from the general tax treatment of the various personal income tax measures. For example, the medical expense tax credit is not refundable either. The idea behind it is that the purpose of these credits is to reduce the tax burden on the amounts expended.
On November 1st, 2011. See this statement in context.