You don't become a great artist by looking at great paintings. You get there by painting all the time. You don't become a mathematician by watching the instructor. You get there by doing the homework. You don't become a famous author by reading Jane Austin and Mark Twain. You get there by writing.
In every case, the thing you must do is create content. However, that's almost impossible on tablets (no keyboard), hard on laptops (small keyboard, no real mouse), and even slightly challenging on desktops (ever try typing out a complex mathematical equation in Latex?).
Today's latest and greatest systems (I'm looking at you, iPad) are really geared toward content consumption, not creation. We should focus more on making it easy for kids to express themselves and then give them the tools that do that.