Handwriting isn't declining; cursive handwriting is. I strongly believe that writing things by hand (handwriting) is an aid to learning, but I don't think learning two different, parallel scripts increases that learning. (I don't object to cursive as an art form--in fact I love it and practice it--but that is something for older kids in art class, not something for writing papers and taking notes while you're still new to writing.)

Those who print all the time can write just as quickly, draw the same diagrams, arrows, underlining, marginalia, and so on, as those who write in cursive or in both scripts. Using a single script instead of two will not lessen the benefits of writing by hand, but using a keyboard instead of printing by hand is more problematic.