I can see the logic in wanting to keep the cabin area uncluttered during landing and takeoff, that debris could really do some damage if it all went flying, but

I can see the logic in wanting to keep the cabin area uncluttered during landing and takeoff, that debris could really do some damage if it all went flying, but the same logic is true regarding all hand-held electronics and most books too (imagine getting hit in the face with a hardcover copy of The C++ Programming Language)