From an environmental perspective, it is better to use surface area which is already built up than pristine natural desert land. The house itself already imposes an ecological cost. A solar roof adds around zero to that cost.

I've heard the stat thrown about that 50% of energy generated is lost to transmission. If that's true then there's efficiency to generation at home.

It probably doesn't figure into anyone's decision but decentralized generation leads to a more resilient "grid". As it stands we are potentially vulnerable to warfare/terrorism attacks on the grid.

Tesla the consumer brand is about being smarter than your neighbor. Wow you have a car which is electric yet more performant than my car? Wow you have solar panels and the aesthetic is better than mine? Wow you're completely off the grid? So much material for dinner parties. In short there is a good value of cool factor for amount of work. And there are people who break the market logic and bake their own bread, plant their own vegetables.

You're right that power from a solar farm will be an option somebody but for many people it's not an option yet. This is something you can do in the near term.