You can buy tickets at those kiosks (if there are any left) but you cannot pick up tickets bought online. Rules changed earlier this year. So, post #7 was correct. Also no longer possible to pick them up at the airport.
You can also pass by any station (possibly one closer to your hotel) on the previous day (like late at night) to save you some time before departure.
The point of using agents is not to have tickets delivered to your hotel but to secure tickets that will probably no longer be available when you arrive in China and also to make sure that you can respect your itinerary, especially if traveling as a family.