If spectrum were leased rather than sold by the FCC then economic pressures could drive shifts in utilization. When bandwidth was allocated to an unnecessary function, it could be repurposed. Central control by the FCC would be desirable - otherwise individual companies reselling their spectrum for other purposes could cause interference by conflicting applications.
I see this as a case of greed, all around.
From the corporate standpoint, why does NYC *not* use all of the TV spectrum efficently? Simple. Because the TV content owners prefer to tie their content to media that charge subscribers by the month, instead of using ad revenues alone. The so-called "dual revenue streams," ads plus subscriptions.
And why is the FCC so bent on grabbing that TV spectrum and selling it to similar walled gardens, such as broadband providers? Simple. Because they stand to rake in the proceeds from the auctions, which will of course ultimately be paid for by the broadband subscribers - you and me.
I have always found it distasteful to see this FCC so bent on grabbing TV spectrum to hand it over to broadband providers, even though the mere addition of 100 MHz of spectrum is not where the big payoff is, for broadband providers. Not when you look at the channel widths being considered for 4G. And worse, the low TV frequencies are less than ideal for cellular systems to boot!