Most business travelers prefer direct flights, because they are faster. (Let's assume it costs £20 in salaries/hour... spending 2 hours in an airport between connecting flights and an hour longer flight time adds up to £60, one way.) And, from experience, traveling is tiring; hanging around in an airport even more so than flying. So, a quick direct flight gets you in a better shape at your destination.
And lastly, the dominant carrier at a hub can ask higher prices, because they have most mileage card owners... and they get them because they offer the best selection of flights.