Persistent storage of keys on a device without a secure element is a bad idea.
The goal here is something you can carry and is secure.
Discussion
It's optional; you can upload your key to an ephemeral session.
Iād say a SeedSigner is better then due to not requiring less specific hardware.
Most people don't build from zero or install a custom firmware, I agree its a incredible minority of users. If you want to appeal to masses you need a slick interface and an smartphone form factor like passport prime.