The value of cryptocurrencies can increase in value by making them usable. Buying, selling and using cryptocurrencies isn't common knowledge. As of now you really have to know what you're doing to get started with no guarantee/backup if your funds get hacked.
Hence the need for practicality, user-friendliness, more security and of course, tactful marketing. If no one knows about the greatest thing ever, it's still worthless. Many of these things can be provided by an ICO creating distributed exchange networks, marketplaces and well-done escrow systems. Still have yet to be perfected and popular. Only a matter of time.