Yeah but, IMO, there is a down side.
When they started charging a "bag" fee passengers stopped using the convenience (and yes, that's all it is) of checking a bag. So now, you have EVERYONE trying to carry on roller bags, which delays the boarding process and causes havoc with unloading, and makes connecting and staying on a schedule more difficult. This is especially a problem because the airlines have fallen into a "we don't want to offend anyone because of social media" policy that prevents them from stopping the idiot with the refrigerator box he calls "carry on" from trying to board the plane. OR the person with 4-5 different bag (none of which fit in the mock up next to the gate). AND this policy increased the number of bags going through the TSA checkpoints; which delays that screening process for EVERYONE, reduces the overall security of the flights, and adds to the frustration of crews, passengers, and airport employees.
Also, when they started charging a "bag"fee it was under the illusion that the increasing cost of fuel was the culprit. Passengers paid without question because everyone was suffering the same fuel cost at the pump. Now, with fuel prices at a low its not seen in a long time, that airlines justification has long expired. THIS suit is more about the collusion in fixing the amount and not about the charge itself.
The more sensible approach would have been to add $15-25 to every ticket cost and let you check a bag for free. Passengers wouldn't see the cost as a gouge and the carry-on bags would have not increased to such a maddening level.