The problem is that some "interactive stuff", like Farmville and Candy Crush and to some degree Angry Birds, is more similar to a Skinner Box than any true interactive environment. Books and puzzle are much less likely to push those buttons.

Also I think there is a worthwhile kinesthetic element on puzzles that is lost online. That could vary from learning to precisely line up puzzle pieces to other things. For instance my younger DS enjoys both the ipad and physical versions of Rush Hour/RHjr. Honestly, setting up the board in physical version is more of a sequencing challenge than solving the puzzles... I know... that makes no sense... however I've seen it again and again. The physical version teachs a superset of the sequencing, planning, and visual skills of the app.