Nor should we surprised
France allowed her colonies independence (without a bloody fight she was certainly going to loose), on the condition that they used the franc (technically the convertible franc).
This would enable France and French companies cheap access to African resources, that is continue what colonialism had been doing <- stealing African resources to subsidize France.
Also, it would prop up the franc as France continued to print money to finance her welfare state (not a judgement on the merits of a welfare state, just a fact that the French weren't taxing enough to afford it).
We shouldn't be too hard with the French though. The Americans largely do the same (see how quickly the leader of an oil producing country is deposed is he declares to ditch the dollar). The Brits gave their empire to the Americans to piggy back off this.