My understanding is that the IMF is working off two justificaitons for capital controls:
1. The financial crisis was contagious via the international mobility of financial assets. American mortgage securities were bought and sold by institutions and funds around the world, some of which are located in developing nations. The revaluation of these assets therefore caused disruption to economies beyond those that originated them.
2. Many advanced economies remain depressed, with the result that both real and nominal interest rates remain low. With domestic returns to capital low, savings are increasingly flowing out of advanced economies and into develping economies where the marginal product of capital is higher. The IMF sees these new capital flows as potentially destabilizing, an argument they used to dismiss until the capital flows of the 2000's proved destabilizing.