That doesn't translate particularly well to less frequent 55 business class seat flights on most of those routes; even if the flights are shorter the arrival times are probably a lot less convenient for most of the executives.
The all-business class model has struggled to be economically viable even on ideal routes like London-NY. Those economy seats give you a lot more flexibility when the business class seats aren't selling.
(And as ghaff pointed out business travellers /= business class; most people travelling on business have an economy ticket sized budget)
For US and European carriers, it's around 75%. Since the cost is 4 - 7x higher than commercial, most people aren't paying for this expensive personally. Not sure about other industries, but for consulting and tech, the standard is to allow a business upgrade on international flights and not domestic.