It essentially comes down to this:
1) We have no idea what will and will not be available in PS.
2) The Devs will be the ones deciding this, not the players.
3) There will be people who will ignore the devs and play their own game, anyways.
4) Up until that point, it is much easier to assume a \'safe\' default as to what to expect. Fantasy, while an extremely varied genre, has certain classic ideas within Western society. These are largely focused on King Arthur, Dungeons and Dragons (esp. Greyhawk), and Lord of the Rings. The more you stay within these ideas, the less likely you are to have to retcon when the game gets better defined. If you have a printing press, and the devs say \"Printing presses won\'t be invented for years to come\", you either exist outside of the normal PS world, making you a pain in the rear to RP with, or you retcon and join the rest of us in the \'real\' PS world. It is, however, so much easier to say, \"Hey, I found out that there are printing presses, I\'m gonna buy one!\". Generally, minimalism is useful in unknown setting situations.
5) Object-oriented differences are one of the worst issues of setting difference you can bring about. With vampires, if the devs decide \"Vampires absolutely do not in any way or form exist in PS\", those who aren\'t in to vamps can just continue thinking they\'re all a bunch of loons, others may decide they\'re loons as a player, but RP believing them, etc. It\'s a heck of a lot harder, however, to go about RPing with someone who has this imaginary pile of paper called a \"Newspaper\" that they made with an imaginary device called a \"Printing Press\".