You are obviously referring to the Pilot or Ingenieur product lines as these are the only lines using the soft iron core. Yes you can question the practicality of the core but no more so than the use of a mechanical watch in the 21st century in the first place. It's a nod to the past and for most has no real practical advantage. Who cares?
Regarding pricing, I don't know where you're coming from. No way is the price of a SS IWC close to that of other brands in gold cases. By the way the size of the iron core is a moot point. The 42mm Fliegerchrono uses a 30mm movement and that is no different than many other manufacturers who use the same movement in equal or substantially larger cases.
Thanks, Mike.