Corporate travel requirements usually require that someone, at least for domestic trips, book a fare in coach for at least short-haul trips. I've booked a trip in coach, but them my upgrade cleared before the trip was ticketed, so when the ticket was issued with a FC fare code, the corporate travel agency pitched a fit and would not allow it (even though the fare that was paid was a coach fare). Thus I think it would be difficult for any airline to sell a premium product to business travelers.

This is also why I think UA's Economy Plus is the best better-than-coach product we'll get anytime soon, other than coach seats that are upgraded to FC ones after the ticket is bought; E+ books into a coach fare code and is much more comfortable than regular coach. I'm happy with it.