the main reason for not implementing crypto currency and bitcoin as a legitimate currency is money laundering and high volatility in the currency. maybe they understand the serious advantages of crypto-currencies, but they are not yet ready to implement these functions in financial and banking systems.
Because its very volatile. Other than that, no reason to call bitcoin is not legit. For me bitcoin is legit but for investment. There is not for currency since its very expensive in transfer fee and low transaction as people know. Not many people use bitcoin as currency.