If you look at Amazon's drop test video (see
http://www.amazon.com/gp/mpd/permalink/m29AN24ZT4S6UX), their Kindle is really durable. There's no reason why it would be less protected while fully strapped inside of a good case. I bought my Kindle partly because of its supposed durability.
It seems like misleading advertising, really.
I pledge no loyalty to Amazon and I'm willing to buy from a competitor if necessary... I'm sure Plastic Logic would love a Kindle convert.