Ultimately, it's just a personal belief that all knowledge should be free as in freedom. SoloKey Hacker Edition in particular lets you run custom firmware, so you can at least be confident in the software side of things, and build upon it.
Open hardware has the benefit of being able to build it yourself, which is the only completely secure option. The downside is, indeed, the ability to easily create malicious clones, and the fact that you simply won't be able to build it yourself for any remotely modern hardware. So yeah, there's really no security benefit to it in terms of hardware.
Proprietary hardware has the upside of needing reverse-engineering to create a malicious clone / part, and the transparent design helps you make sure that they can't do a sloppy job at it.
It's a shame that tradeoffs have to be made once technology reaches a certain level of complexity, but alas.
Open hardware has the benefit of being able to build it yourself, which is the only completely secure option. The downside is, indeed, the ability to easily create malicious clones, and the fact that you simply won't be able to build it yourself for any remotely modern hardware. So yeah, there's really no security benefit to it in terms of hardware.
Proprietary hardware has the upside of needing reverse-engineering to create a malicious clone / part, and the transparent design helps you make sure that they can't do a sloppy job at it.
It's a shame that tradeoffs have to be made once technology reaches a certain level of complexity, but alas.