Originally posted by ChessNut
I think it's to give the rider the illusion of speed. Makes them feel like they are going faster than they really are. As humans we are very impatient aren't we?
Ok, after some thought my view is this: It is important to make sure that the rider is not sloping backwards when the escalator flattens out as he will then try to regain his balance by taking a step backwards into the person or step behind him, will then fall over, and will probably be sucked into the machinery and die.
If the handrail goes slower than the steps it will tend make the rider slope backwards, so it's best to err on the safe side and make the handrail a bit faster than the steps. This of course makes the rider slope forwards a bit, but people are not particularly likely to fall over if they are sloping forwards because they can take a step forward to correct their balance, which is the way they want to go anyway.