I get it and know about the history of this in the USA.  I've got to hope though that this would be helpful to the generation that is finding it hardest to buy a house or pay off it's mortgage.  Maybe set out a clause that interest is tax deductible if the proceeds of which are applied to the mortgage principal (ie: attracting a smart debt reduction plan).  Most people have 30 year amortizations, so a government incentive to reduce that amortization should be encouraged.