I think that there are several factors here at play. Tesla wants to sell electric cars, and to sell solar generated electricity and storage devices. It’s a complex and brand-new environment, and they need a lot of money to scale up and sell a lot of those products at cheaper prices. I suspect they are going suburban to unlock a market of wealthy customers that are not going solar for aesthetic reasons, or homeowner who need to change their roofs.
As they are doing with cars, they seek premium products because they are expensive, so they can have better margins, thus get more money to invest. Then they reiterate. This was the plan from the beginning for Model 3, and could be the plan for solar roofs too.
Tesla needs to scale and do cheaper stuff, but this can’t be done overnight. For an urban environment, they are already working on autonomous ride-sharing cars and bus, which would be extremely beneficial. Also, there is the whole grid topic: this article is quite technical but interesting about the future of the grid that Tesla has in mind.