Maybe they don't want solar or don't want their roof facing that direction. Let people do what they want with their belongings. If south facing roofs have higher demand it will be reflected in the value of the home.
They will when the cost of traditional electricity is priced to better reflect it's environmental impact.
In fact, I personally think nobody should be permitted to not have solar in a new building in 2016. You can't remove the seatbelts from your car in 2016. You can't build a new building with asbestos in 2016 and you can't turn your semi-auto rifle into a fully-auto (in most states).
Just because you own it, doesn't mean you can do anything you want, that argument makes no sense.
