I wouldn't call the authenticator "basic security"; it's a very high level of additional security. For a video game.

And if you don't have a smartphone (spoilers you probably do) and you wanted an authenticator you could buy the token or emulate it on the OS of your choice...

http://developer.android.com/guide/developing/tools/emulator...

or on any java device apparently:

http://arenabooster.marisil.org/bma.htm

I believe that they also now allow authentication over SMS.

Edit: it's not quite an authenticator: http://us.battle.net/support/en/article/battlenet-sms-protec...