well getting back to your question, lightning aside and even connections for that matter.
I used to have a NAS ... it went up and died ... and I never replaced it.
When my kids were living with me I had my main listening area running JRiver as server and three clients. Now I only really have one and an occasional second client on a laptop. The NAS was slow, and a pain. Looking into what was available at the time and estimating how many hard drives I was going to need (2tb drives were then the norm, 3tb drives were just starting to be affordable) a 4 to 6 bay fast NAS was expensive.
Looking at the money, I also wanted to avoid an additional machine running so I decided to build a silent PC (well almost silent). I put an i5 in it, a mini-atx motherboard in a Lian LI box that is pretty small ... and I can have up to seven drives+SSDs and two optical drives (at the time I used 6 HDs. Now with 4tb drives I don't need as many, but hey they are there.)
No worries about not having system events kick in for autoimport, fast access across the network, it can be a JRiver renderer directly, and you don't need 2 machines on if just running your main "entertainment area". If you configure the wake on lan functions, even energy efficiency shouldn't be an issue for most people. Also very simple headless operation using Teamviewer or something like it with a client ... no worries about Linux/Windows issues (or in my case Linux ignorance,).
Now I'm not sure why you have the server machine running 20 meters away, but you have that streamer so you chose to go that route already (I like to use JRiver as renderer myself). Still you can set up a server PC for MC (especially if its not rendering 4k videos) for less than an equivalent performing NAS. (chime in if this has changed guys, but I don't think so)
However, if I travelled all the time and had an office or clients external to my local network, thats where a NAS would be nice to have I think. Now I just tap into my music using my ipad at my local pub so problmes that can happen with external wake-ups aren't a big deal. Maybe if I had a big family adding/using the content all the time a NAS would be worth it. And there is this cool QNAP version of JRiver now that didn't exist before which might also enter into the equation.
Anyway I think most people don't need a NAS and are just complicating their life and spending money that they don't need to. If you don't need silence, an old computer maybe with an upgrade or 2 would be fine. You want straight ethernet or wifi no problem. 20 meters, not an issue. If you aren't using it as a renderer an i3 would be fine for most things. And now with Iris built in graphics, you could get a new gen NUC or similar to be a renderer for MADVR video playback (maybe no interlacing and stuff, but it should be pretty good).
I think you can protect your electronics from most anything these days, but I don't think the question to buy a NAS or not is really linked. If lots of people contribute and access at the same time the content on a bunch of clients, or you want a very stable external connection, look into one. If not I'd just use a PC as a server myself.
good luck with the storms in Johannesburg