I'm a big fan of Southwest Airlines. When I lived in Baltimore is was the preferred carrier for any business trip out of BWI. I would forgo other airlines and direct flights to fly Southwest. They are the easiest to earn a free ticket and I could decide who was sitting next to me. (Click here for my older SWA posts)
Now they launched Business Select, apparently you pay a small premium which entitles you to board with the A group. I guess you don't need to race to print your board pass any longer. There is greater flexibility in changing your ticket as well as getting a full refund. You'll also earn more frequently flier points!
They also launched Business as well which doesn't have preferred boarding.
Smells like enhanced yield management.
Could it be that business travelers are competitive for the A slots and would gladly forgo $$s to skip the line?
Could the business traveler be the only people who earn free tickets normally and would pay the extra charge since it's really their business paying the cost?