Well in my opinion we should not really restrict screen time for kids. They should have the opportunity to experience cutting edge technology that might have a good impact on their future.
The thing is that we need to find out more ways to encourage physical activities in kids with the help of these digital devices. Just as it says in the article... there should be more products that do not encourage addiction or overuse of smart mobile devices.
Bottom line is that as in every other thing, there are pros and cons in this as well. We just need to use them wisely. :)