There are tons of interesting things you can do with cryptocurrency and blockchains. Most are financial products, but some are just easier ways to develop software. None of this justifies the insane valuations of most coins, but I have built products that would not have been possible in the pre-ethereum world.
For example, who wouldn't want a system that forces banks to track customer balances in a secure, private, and auditable data structure? This is completely possible with cryptography that was researched as a byproduct of cryptocurrency development. It would be a marginal improvement on the existing banking system, but it would provide real, practical use and would improve confidence in the banking system.