One data point doesn't mean it's a design flaw. Most people aren't going to take their MBP offroading, so why should they make compromises just to serve this small, but now vocal minority?
I think the point is that when the computer is powered off and the lid is closed, there is absolutely no reason it should ever power on by itself.
Maybe I'm overstating the variability in MBP users, but I hope you get my point.