the store will be closed once the game is live. consider it pay to build the world and your role in it. unless owning a kingdom is your idea of winning then yes. but there is no really "winning" titles can be lost, land lost, buildings demolished or abandoned.
so no, it give you no game play advantage. simply allows you to play the way you want from the start. your horses can be stolen killed or die, so unless you are a breeder, you will need to get a new one.
p.s the CEO has stated "the moment this game has a cash shop as a source of revenue is the moment we have failed as developers." so there will be no cash shop after launch of the game.