I'm not saying cryptocurrencies shouldn't exist, only that they are not at this time a serious or practical alternative except for very unique scenarios that are generally outside the scope of the average citizen, especially in the developing world. In the developing world, very often, even access to computers, electricity, and internet are serious obstacles, not to mention a gap in technical literacy compared to the developed world.
Also, having options is better than not having them. Sure, there's the international wire system, but it wouldn't hurt to give it some competition.