I do find it bizarre that it's separated so much. They're even separating the Mac version, requiring you to repurchase it again to play it on Mac.

To give some examples, I bought Rift on PC, and can play it on Steam by simply downloading it. I can then play on or off Steam without any issues. I bought WoW on PC, but I can play it on PC or Mac by simply downloading it. I don't have to buy it again.

I'm pretty sure nearly every MMO is this way, except FFXIV, and I don't quite understand why.