I am still of the opinion that checked bags should be free (at least the first) but people should have to pay for a large carryon (basically all the roller bags, but not briefcases, shoulderbags, small backpacks, purses...anything that can fit under the seat is free, if it needs to go in overhead or you have 2, you have to pay).
Still there is a bit of an odd info in this story. It seems that there is evidence that the checked bag fees actually improve on-time departure by limiting baggage handling. That sounds like something that could make sense, but it is also definitely true that the larger number of carry on bags makes boarding slower, in fact, in most flights now, there are at least a few people who must gate check, and that seems like it would be slowing things down worse than having a few extra checked bags to begin with. So my question is: did the checked bag fees really improve on-time departure, or is the on-time departure related to other changes that happened in parallel (mostly fewer flights, but also better scheduling and increased time built in)?
The answer to the question in the lead should be obvious: airlines charge because they can.