Of course it could be seen as a good idea. As a continent Africa provides a huge number of competitive athletes to the world stage. Why shouldn't they have the opportunity to showcase their talents on their own continent?
In response to MarleneB- whilst there are a number of African countries currently in positions of political unrest that is not the continent as a whole and South Africa showed at the recent Soccer World Cup the potential and ability they have to stage an event on the world stage.
A real worry is that many see a problem with a country within Africa as a problem within the African continent as a whole. Having recently visited Morocco and witnessed at first hand it is a very stable country so the risk in many cases is that people only consider Africa as a whole and not it's individual countries. You hear of people that went to Africa to Climb Kilimanjiro however you don't hear people say they travelled to Europe to Climb Mont Blanc or Asia to climb Everest.