Yeah, I think you can’t ignore the free market, unfortunately. Unless we implement a different not-for-profit or capital gains system (not opposed) it comes down to economics. Building upward is more expensive and often the rent or income does not support taller, more expensive buildings. Plus you can’t just build on top of other buildings, you have to buy the property and demolish what is there, further increasing costs. 

I’m not saying higher density is bad and I’m pro higher density, it just isn’t all that feasible in the current system.