Have you even considered that the extra fee is being used as a deterrent to those that think roll-on bags are carry-on bags? It is to the point of ridiculous. When a carry-on/roll-on bag weighs as much as a small child, they should have to purchase a seat for it! Honestly, if you have to roll your carry-on bag because it is too heavy to carry through the airport, then it has no business being in an overhead bin. The airlines need to place further restrictions on carry-on bags. They should only be carry-on, not roll-on. they shouldn't weigh any more than 15 pounds, (enough to carry a couple of baby bottles, baby food, some medications, some wipes, diapers, and a light change of clothes for a small child). When you equate that to the business world, a briefcase AND a small carry-on bag should be allowed, but the two combined should weigh no more than 15 pounds. Common sense is the rule. People are cramming as much as they can in roll-on bags so they can avoid the check-in baggage fees. When they implemented the check-in baggage fees they should've also changed the rules that apply to carry-on bags. I'm not saying roll-on bags shouldn't be allowed, but smaller weight restriction should be enforced on all of them. Fifteen pounds should be the max.