Cave Johnson always had his priorities straight. If you notice, the Long Fall Boot is armor "for the Portal Device." It's not designed to protect the test subject. Those are easily replaceable, after all. The Long Fall Boot ensures a test subject lands on her feet so she doesn't fall and land on the Portal Device. Those are way more expensive to replace!
These Portal 2 Socks are modeled after the Long Fall Boot but will not -- we repeat, WILL NOT -- right you if you try to land on your head. ThinkGeek's Legal Department recommends that you always jump feet first.