But as a colleague told me years ago: never travel with anything you aren't prepared to lose, because You Never Know.
When I take a guitar with me on the road, I take one of these: http://www.brunner-guitars.com/?page_id=591 Not the cheapest, but it'll fit in the overhead every time.
Meanwhile, in the rest of the world, you typically get one bag checked in as part of your ticket. So there's no economic incentive to try and shove half your possessions into a small overhead compartment.
Then it gets sillier when they gate-check the luggage anyhow. To deal with the problems caused by not checking luggage "for free", they are ... checking a random selection of luggage at the gate. In a less efficient manner. In a way that slows boarding.
The most amazing part is that this situation has now totally inverted the order of boarding. It used to be that boarding last or near-last was a privilege. Who the hell wants to sit in a cramped plane for even longer? Now it's a curse.
Small changes can have surprising consequences.