It's not pay to win in the slightest. The ability to spend money on a game to purchase visual changes that don't affect the power balance completely fits the free to play model. For example, League of Legends which sells skins (cosmetics; exactly the same concept) is not pay to win.
Any game that has items that can be obtained through cash purchase is p2p. pay 2 win does not have to be something that gives you an advantage. pay 2 win is any item that is obtainable by purchasing with real money only.
Not everyone plays games to kill people/build stuff/run around. Some people play games for what they can customize on there character etc. So adding cash only visual items makes it pay 2 win for someone who plays for the cool customization's.
Any game that allows an item to be purchased for real world money is pay 2 win.
**edit**
Leaving my typo up there but I did not mean p2p meant p2w.