By all means, let's go for the real-world approach and let the official exchange rate float free. But you have to do it for everything, not just when people are trying to go from pesos to dollars on their Argentine credit cards.
Ultimately, I'm not advocating for the gov. to go 4.6 on both sides of the exchange (although under current policy if the official rate is 4.6, then, well, ummm.... you should be able to transact either direction at around 4.6). Instead, I'm advocating for the gov. to abandon the official rate and let the value of the peso be determined by the market. Obviously, this would not be 4.6.