You're free to crush, sit on, break, do anything you want to my bag, but if you break my macbook pro, then I'll go to the ends of the earth to make sure you're billed the $3,000 it will cost me to replace it.
Besides, my rollaboard goes in the overhead, wheels in, and my laptop comes with me and sits against the wall (I always sit in window).
Airlines are lucky this country doesn't have a high speed rail system. They'd all be out of business by now if Acela was as good as the TGV.