I think that's a very fair comment for the present generations of tech users, however I can imagine a similar argument posted way back when GUI's first started appearing on desktops, why would you want a mouse and windows, surely having one thing at a time in a text box on a text display makes you more efficient as you aren't distracted by shiny stuff.
Not sure if things will change for future generations. My kids are under 10 and are so comfortable jumping from using a tablet device, to a keyboard and mouse on a desktop then to a laptop trackpad, it's frightening how old I feel as they tut and laugh at me, a 25 year IT veteran, trying to use a tablet the same as I use a desktop keyboard and mouse! They have learned already that each device requires a different way of working, me being a sad old git of 40 years old simply needs time to adapt, they don't.
People adapt very quickly to changing tech. 30 years ago if you said we'd have 50" TVs in our homes linked to a world-wide network of data that can shifted to pocket devices in a split-second anywhere on the planet, then up onto a home computer no bigger than a slim brief case within another split-second, you'd have been patted on the head and told it was real life not Star Trek!