Current UX Issues of the Blockchain Technology
Alec Vishmidt

I absolutely agree with your main point that bad UX stands in the way of mass adoption. Blockchain technology needs more UX experts!

Just a comment on transaction speed and cost. Blockchain technology has an inherent trilemma: Security, Decentralization and Scalability. There is no known way to solve all of these dimensions in one product or service. When you refer to blockchains that offer greater speed they typically compromise on security or decentralization.