I find it totally valid, actually. Account creation was never necessary when GameCenter was supported (or, in the old, old days, maybe something like OpenFeint). For years, GameCenter was your account. Buy game, start playing right away.
Again this is a subject for a more dedicated thread, but I have to add that it's astonishing to me that online multiplayer was way better in 2012 than it is now.
On topic: I'm still going to buy it. They had me at "campaign." I love that stuff.