Islamic History hasn't been ALL bad either. There are many examples of good Islamic societies. During the height of the Caliphate in Baghdad, Jews and Christians lived in peace as compared to the persecution of faith that went on in Europe at that time. There was a flowering of literature and philosophy and many examples of great 'free spirits' who flourished under Islamic Society, such as (off the top of my head) Rumi, Ibn Arabi, Ibn Sina, Al-Jahiz and many, many others.
All your arguments aside, the greatest testimony to Mohammad's (pbuh) prophethood comes from the faith of those nearest to him. His best friend embraced Islam, his wife embraced Islam, his cousin and his slave embraced Islam. Some of his companions were always with him call it 24/7 surveillance if you will. In case you missed the point every aspect of his life is covered, from his wife we learn how he was in bed, from his slave we learn how he treated them, from his companions it is difficult to make out who he loved more, the Salman of Persia or the Abu Bakr of Mecca.