Density also matters if you're trying to avoid sprawl. A city like Houston basically requires you to own a car and drive everywhere, because public transit will never be able to keep up with the construction nor will the density be high enough to make it economically viable.
Cost of building a tower is much more than something like rowhouses, multiplexes. Cities like Toronto and Vancouver bypass the "missing middle". So it's mostly single family homes with various "tower node districts".
Yes, towers are expensive, but building them doesn't make the existing SFHs more expensive. Maybe tower building and rising home prices both coincide with certain economic trends, post hoc ergo propter hoc.
Not really. Dallas is an example of a metro area that has extended sprawl as far as it can go. A ton of new highways have been built out but growth in car usage and population have eaten back all the gains. There will never be enough land to make the sprawl work. As a result home prices there are jumping just like everywhere else. No one wants a 2 hour commute.
Not as far as it can go. It can still go many dozens of miles in every direction, and has, and will continue. Companies are following employees to the burbs and employees are moving even more with the uptick of remote work. Home prices are jumping due to population, but sprawl continues unabated.
Density doesn’t matter right up until you hit the limits of what the highways will handle. Then you’ll suddenly wish you’d built dense enough for light rail to alleviate the load on common routes.
There are areas in Canada where building massive towers has been premature and also led to increase in costs.