That's true for our generation, but future generations might lose the hability to do both as we move to a 100% digital era.

That's kind of the reasoning I'm rejecting. In the year 1915, Americans could on average tie 100 knots (can't cite the source, but yes it was something I once read), and I'm sure many more were a bit more seafaring and horse riding. As we developed cars and planes and clips, all those skills have receded. They aren't gone, we can all tie our shoes and swim in a pool, but these are physical actions, I doubt we'll ever lose them. And yes, kids are dumb, but eventually they become adults who understand that writing has a place in their lives.