I've seen it taken a step further. I was on a completely full flight and the gate agent solicited people to give up their roller bags in exchange to "express" board.

She must have got 25 people to give up their huge roller bag. The flight boarded in a flash, no one who kept their bag had to search very hard to find bin room, even the very last person on the plane found room for their bag and sat right down.

Seems like a good tool if used proactively like the lady who worked my flight. She was all alone and the door closed 5 minutes early. I like it! More airlines should pay attention.