Capital controls would need to be very pervasive to have any effectiveness, implying prohibitive costs and setting back financial development by several decades.
The option of free floating has in theory a number of advantages: i) it would not require to accumulate reserves to stabilize the exchange rate; ii) it would preserve monetary policy autonomy; iii) it would protect each country from external monetary shocks; iv) markets would enforce an effective and symmetrical discipline on national policies across all countries; v) it would avoid imbalances and instability as long as each country maintained its own house in order.