The Book is also Just a Book
Vertex,

Is it not true that Muslims believe that the actions and life of the Prophet are an ideal example of how Man should live ? In this context his marriage to Aisha would appear to condone child marriages, as any muslim could justify the practice as simply following the actions of the Prophet.

If you believe that this was justified in 7th century Arabia but is incompatible in todays world, then you are implying that the message of the Qur`an & the Hadiths need to be interpreted in the light of modern sensibilities and is therefore not applicable for all times in its original form.