Dare I whisper "cost and what they can get away with"
No, please don't whisper it... Shout it out loud: That we can all hear when you're coming and leave before you arrive.
Some of you seem to be labouring under the illusion that industry safety criteria are knocked out in biro on the back of a beer mat by a few blokes in a pub in between wednesday night Karaoke numbers. Naturally, this means that armed with a few semi-digested facts, a DVD of Air Crash Investigation and enough time on your hands to marshall the resultant purée into something resembling coherence you believe that you can now make safety pronouncements with equal validity to the so-called experts.
This is a forum intended for use by people who are part of a team that take the safety of their customers very seriously indeed: They usually work for a company that shares that view, and work on-board aircraft that have been designed and tested over a long period of time by people who can prove that they are qualified to do so. If you feel that strongly about what is essentially T-Shirt sloganeering the path to safety, then why not start a Facebook cause and get your friends to "Like" if they agree: Meanwhile, the professionals can get on with what matters.
The original question has been answered, and yes, the OP had every right to pose such a question: PPRuNe at its best is when these questions are asked by customers, and then answered by people in the business who know - PPRuNe at its worst is when the answers are then ignored.