This source seems to think differently. In either event, explosives aren't something you really want passengers to have, and multiple passengers could have multiple shoes. Are you seriously suggesting that they not screen shoes now?
The linked source agrees with me, 50g would not be enough to do serious damage, you need to have 100g to do serious damage to a car, which (for explosives as opposed to impact) is not much stronger than an airplane fuselage. http://news.bbc.co.uk/2/hi/854...
Being required to check your own bag is OK. Although some of the searches bags are subject to is questionable, but that's a slightly different topic.
Shoe screening has never been acceptable, especially because it's ineffective.