I've googled "unraid wireless" a few times and the results show there to be at least one thread from every year in the past few years from someone requesting the feature or wondering how to do it.
I live in a small one bedroom apartment where the only wired access to the internet is at a small desk between my bathroom and bedroom doors. There is not enough space there for my unRAID server and my gaming PC. I have placed my unRAID server in my living room by the TV because that is the only place I really have space. I also plan on having it run a gaming VM to play VR off of in the future (so I don't have to move my gaming PC back and forth for VR and normal PC games).
I purchased an AC power adapter like this one based on most threads saying that is the best option... but I think my apartment building has too much interference on the AC power lines because I only get around 6megabits/sec... its not like its going that far either, my apartment is small. Running an Ethernet cable across the floor in front of doorways is not an option, and since I am renting the place I can't drill into the walls or tear up the carpet to run cables either... I own a pcie wireless card that I could add to my server but unRAID doesn't support it. With wireless AC speeds approaching the normal read/write speeds of a traditional HDD, I don't see a good argument to not support it other than the difficulty of implementation which I would not know of. Even just requiring a physical connection for initial setup is fine I think.
I feel like there could be a lot of potential unRAID users that may turn away from using it because they won't be able to run an Ethernet cable to their machine. Like pwm said in this thread (the most recent thread I could find asking about the feature):
Even though it is optimal to have a wired connection, it is not always practical/possible, especially when wireless would be a better/faster solution for people like me where any possible wired option is actually slower than my wireless speeds... so slow that I can't even stream plex movies to my chromecast from it...
Pardon the lengthy post... I'm new here, let me know if I need to say something differently.