Interesting discussion.
I think these things should be applied with more nuance, a blanket hit on investment properties drags in people who have circumstances not really appropriate for it.
For a lot of people an investment property is effectively their super, without the means or knowledge to set up a self managed super fund provision.
Seems silly to force people to invest in super on one hand and then penalise them on the other. Much like the 3 million super provision, I think these things should be targeted based on value. Apply it to people with investment properties with a value of 2 million and above for example.
I think negative gearing is highly overblown as well, I've always considered it fool's gold. People forget negative gearing relies on your investment making a loss. Tax breaks on other income don't cancel out that loss so you are relying on capital which doesn't exist unless you sell the property and them you have to pay capital gains. If it is a long investment the capital can be substantial but so are the year on year losses.
Anyone who is negatively geared would almost always be better served with a different investment in my experience.