i know what you're saying porsche building extra stregnth into the cab, but the cab was designed for street use (convertable=street car) and track events although "safer", can be more prone to mistakes causing heavier off axis impacts. if you hit a tire wall at 60+ it can rip most cars apart.
although it's "your" head, it's the insurance companies who pretty make up the saftey rules, without insurance we couldn't even touch these tracks, unfortunately some of the rules don't appeal to everyone.
i just think from a safety standpoint taking a cab w/o bar to the track is just asking for something to happen, i've been involved with scca regionals/nationals for years and have seen very simple mistakes turn into rollovers/collisions. we need track events to fully understand our beasts and at those speeds you are always learning, when you learn you make mistakes.
this is my story and i'm sticking to it