Free-software advocates don't "completely ignore" it. rms has discussed it on multiple occasions.
1. On "Free Hardware" (1999)
* https://paste.textboard.org/ca386358/raw
* https://www.linuxtoday.com/infrastructure/richard-stallman-on-free-hardware/
2. Free Hardware and Free Hardware Designs (2015)
https://www.gnu.org/philosophy/free-hardware-designs.en.html
The second article's section "Must We Reject Nonfree Digital Hardware?" is particularly relevant, esp. paragraph 7.
In the mind of rms, libre hardware is less at issue since you can't run modified versions of hardware as readily as you can modified versions of software. In his own words:
Thus, the four freedoms don't give users today collective control over a hardware design as they give users collective control over a program. That's where the reasoning showing that all software must be free fails to apply to today's hardware technology.
About the second part of your question:
[W]hen will we have free optical readers or something like that?
Someone would have to develop libre hardware designs, and then multiple parties would have to manufacture/implement the specification.
Free hardware will probably not become very prevalent until one or both of these conditions are met:
* Hardware fabrication becomes feasible on an individual level (not mass-production).
* Libre hardware becomes required to run libre software.