I agree with the above, but here's some interesting add ons...
+ One of the reasons carry-ons have increased is due to baggage being lost. It got so bad, and so random, people always feel they need to have an extra set of clothes in their carry-on just in case.
+ Will we see an increase of people buying those big coats with 20+ pockets in them? You know, the ones which can even hold a whole set of clothes, your iPad, etc.. Many geeks are using those now in order to really have two carry-ons instead of one. Or are we now going to have a coat fee if this idea takes off?
+ Finally, Jimmy Carter tried pushing for us to change to metric...along with renewable energy...back in the 1970's. Republicans had a field day stating it would collapse American business due to the cost. Just sayin'...