Why? You can still set Google as your homepage.
Most likely because thats the first way he saw to do it, so thats what he remembers. Forgetting the old way and learning a new way is just too difficult. Also, you're implying he knows how to set the homepage.
In my grandfather's day there were no power tools. A drill had a crank. In my dad's day carpenters used clawhammers to build houses, now they have nail guns.
The difference is, your grandfather was likely able to understand at least the basics of how a power drill works. But computers, to the general public, are still just a magic box.
Perhaps a better phrasing of the point is though the new interface may technically be better, how much of an improvement is it? What is the cost of learning/teaching the new interface? And remember, just because you can pick it up in under an hour does not mean that Average Joe and Grandma can.
This restaurant was advertising breakfast any time. So I ordered french toast in the renaissance. - Steven Wright, comedian