My modern phone is useful. It has replaced so many things: I no longer carry a paper notebook, for example. I no longer spend money on watches. I have a map with me. If I get in a bind, I can get help - I have some security because of the phone. I have a translator app in my phone! As imperfect as it is, it is better than all of the tools before it. I can pay for stuff with it if I'd like to - and I do, every time I ride the bus. I don't need to print out airplane tickets any more and a slew of other useful things.

I wish everyone had a telephone, as the world would improve a bit. I don't really understand why you think it is a dumb idea.