Classrooms are still full of MacBooks and iPads because the first modern tablets with active stylus support came out after the fall semester of last year started (meaning the yearly push for students to buy new computers hasn't happened yet) and Microsoft has done a completely terrible job of marketing them.

Also, at least at my college, effectively no one takes notes with their laptops or iPads anyway. If they're out in class, it's for Facebook or something else totally unrelated to the class itself. Notes are still written down on good ol' paper.