In my 44 years' experience in the industry, I have always said that whenever you introduce something to an escalator or moving walk you can also introduce other hazards, so you have to be careful. This subject is no different and whether you love them or loathe them they are with us to stay. Architects tend to dislike things that interfere with aesthetics and this is one of those things. That having been said, I have lost count of how many accident investigations have landed on my desk involving luggage on escalators. It is a well known fact that luggage is involved with many incidents on escalators and the outcomes can be quite severe. It is also a known fact that shopping trolleys and luggage carts on escalators can also cause severe accidents, my MSc dissertation at the University of Northampton published in 2005 researched this very subject. (copy available on request)