That is the title of this piece by Barnaby Rogerson in the Spectator. There are three beautiful pieces of medieval art (two Persian and one Turkish), and those alone are worth the price of the click. There is, of course, a short essay explaining why there is now so much resistance to depicting Mohammed in art (of both the high and low brow variety). Check it out:

Whatever the heritage of their medieval past, Sunni Islam — in the Arab-speaking Middle East — had decisively turned its back on depictions of the Prophet well before the 18th-century emergence of Wahhabism. Once again there are no definite answers. It may have been a gut reaction to the magnificent art produced by their Iranian Shiite rivals but it also reflects a very real fear that Mohammed was slowly being turned into a demi-god and that in the process his actual prophetic message would be ignored. This was especially true in the far eastern frontiers of Islam, such as India and Indonesia (numerically the two largest Muslim nations in the world) with their ancient syncretic traditions. So the attack on imagery can also be seen to have a constructive element embedded within it, concentrating all attention on the text of the Koran and reinforcing the Arab nature of that revelation.

Take this as you will. My instinct is to suspect “the Arab nature of that revelation” as the initial reason for this change in Islamic aesthetics. That is to say, I suspect that a medieval notion of Arab chauvinism is responsible for the shift.