Would we want to go back to playing Civ IV without what Beyond the Sword adds? No. But should we have to pay this much for the privilege of balancing a game that, by the very intent of this expansion, its developers clearly feel needs it? Again, no.
An uncertain step from Firaxis, then, a sign perhaps of just how hard it is to refine a title that is so revered and defined without damaging what makes it so good.