The cold temperature was indeed the cause of the O-ring failure. Professor Richard Feynman who was part of the investigative committee proved this using nothing more than a section of O-ring and a beaker of ice water. Those with a dog in the fight refused to believe such a simplistic answer and made his observations part of the committee report appendix only, It seems more likely that they did this in a fit of pique as Feynman went public with his findings.

Feynman was had stage four cancer at the time and didn't need to commit himself to such an ordeal and this was his final act as it were and one I believe made him all the more nobler for it as it forced all those involved to change their working practices re the shuttle.