The economics of gate checking

One cannot help but wonder whether airlines would actually prefer that passengers gate check bags, instead of paying $30-$40 to check back at the check in counter in the main terminal. It could well be that the economics of the transaction are actually favorable to the airline because 

1. Staffing needs at the front of the airport are reduced, also you need fewer people moving bags between there and the tarmac

2. There's a lower propensity of bags to get lost

3. Passengers pack less stuff, saving on fuel costs and even perhaps allowing for less luggage space on the plane as a whole and more seating

4. The costs of scanning bags is more externalized to the TSA if passengers get them to the plane.

There are probably many more reasons. I bet it pencils out. Time to board.