Why not make residential rent tax-deductible?

Your ideas are good but taxing the income-equivalent of the family home is political suicide and will stop people from considering otherwise good ideas. You can achieve the same end by making residential rent tax deductible and owner occupation tax-exempt (rather than the other way around which is your current policy). This will mean there are no losers (apart from - possibly - a bit more tax on the wealthy), some winners, and you'll still achieve your goal of tax/investment neutrality. Note that when GST was introduced, the one local exemption was residential rent.