It has come to my attention, that there are people, be they tourists or others, who are a little confused about how to travel on and about the metro.
Within the US, we drive on the right side of the road. In multi-lane roads, the expectation is that the right most lane is where the slower (or more law-abiding) drivers are, and the left lane is for passing.
Following this logic, on escalators or moving walkways, the expectation is that you (and your stuff) will stand to the right or walk on the left.
If you are motion-challenged - due to number of bags, weight of bags, height of heels, general tiredness or any other reason, please either stand on the right, allowing the motion unimpeded to continue on.
If you are motion-challenged but wish to move forward partially on your own power, see if you can find an open space on the right so that you are out of the way of people moving at standard speed.
The same applies in the hallways and platforms, but there is also the addition of two way traffic and the need to be courteous of folks attempting to walk at normal speed in both directions. No one is saying you have to move at the highest pace, just be aware that others wish to do so, and try to allow space for them to do so.
I understand it is much easier to talk to people when you stand side by side on the escalator, but particularly on some of the very long metro escalators, there are people who need to move. Sure they may seem rushed, but since you don't know where they are going, just leave them space to do their thing and you can enjoy the ride safely on the right.