I would say usability and adoption are the two main factors of an successful cryptocurrency project.
We have seen a lot of times lately:
- usability without adoption: Byteball, NXT, Stratis, etc. (super features, cheap, fast enough and nobody use this platforms (no use cases or very few).
- adoption without usability: Bitcoin, Ethereum both couldn't handle so many users, transactions prices spiked, network was slow and not usable.