>>Companies do not have a financial inventive to consciously cripple their very highly paid, very difficult to hire developers' productivity.

I highly doubt that:

a) most companies have done studies to measure correlations between office plan types and developer productivity

b) they even know how to measure developer productivity accurately

On the other hand, they can easily measure headcount per square foot. It's a simple division that even the stupidest executive can perform. The other stuff is just hand-waved away.