Back in the day it was essential, in case you bricked your Wii, but now personally I see little point because:
1. Initially I installed The homebrew channel, a ULGX forwarder and 3 cIOS on my main Wii with no issues. Since then I haven't installed anything else, and don't plan on installing anything else, so pretty unlikely that I will brick my Wii by installing something bad. If I do get into installing Wiiware wads, then they will be installed to emuNAND.
2. I have 4.3 so nothing can currently update my Wii. Back in the day there was the fear than Nintendo would issue an update that would brick a modded Wii. This update could come on a game disk or across WiFi. There are no new game disks now so that route is out, and my Wii isn't connected to WiFi. Even if I was on WiFi it's unlikely Nintendo will send a 4.4 update now, as they haven't sent a Wii update for over 10 years.
3. Even if my Wii did get bricked, I could buy a second hand replacement for relatively nothing. A Wii console without accessories costs about £10. Back in the day they cost hundreds of pounds (or dollars). But now second hand ones are abundant and dirt cheap (provided you don't care if they are scratched). I myself have a Wii and 2 spares!
Fair enough, all valid points, especially that last one, but there's no downside to installing these things.
In fact some priiloader system menu hacks are neat, like the newly released 480p system menu fix system menu hack, region free, moving the disc channel, etc.and some settings like autobooting or one of my personal favorites the disable the shutdown to idle setting, so by default the Wii turns off to red, instead of yellow. If you leave a portable hdd always connected to a USB port, leaving it set to idle will seriously increase the wear and tear on the drive as it's always spinning. That may not be applicable to you depending on the hardware u use or your config
Another concern is when kids play on the console they may accidentally do something stupid if they somehow gain access to the wrong homebrew app. Unlikely, but still not impossible. That being said the wrong homebrew could still brick a console with priiloader installed, so not even that can fully protect you from kids. You can lock or keep risky apps off your media, but if u got novice pre-teens testing things out that they read online, it's more likely they'll try a theme or custom channel or something than remove priiloader
I agree Priiloader has some useful hacks, but I guess that I'm unusual in that none of them are useful for me.
My Wii is revision 60 so doesn't need the 480p fix.
I use ULGX to play games and that region frees them, so I don't need the region free setting.
I have no desire to move the disk channel or autoboot.
A Wii will only shutdown to yellow if you have WiFi enabled and the Wiiconnect24 service switched on. I have both disabled. I realise some people may use Riiconnect, in which case it is useful for them.
There is no power to my hard disk in standby. Probably because it goes to red standby.
I'm not concerned about someone else breaking my Wii because I have 2 SD Cards, one with all the dangerous homebrew I used when setting up the Wii, such as hackmii and YAWMM. The one in the Wii only has ULGX and some emulators. In ULGX i have locked the settings. I don't have young kids, but even if I did there isn't much anyone could do to break anything really, and I have backups of my SD Card and USB disk so as long as it wasn't bricked I could restore them.
I get it, it's kind of like owning a car that you never drive but sit in from time to time or just drive around the parking lot or something, there's no real need to wear a seat belt, even though it certainly doesn't hurt and takes very little effort, I get why you wouldn't necessarily feel the need. But I'll still tell people that they should ALWAYS wear a seat belt, and respect their freedom to make their own decisions
Anyway, I would like to thank @XFlak for Modmii. It's an amazingly slick and extremely useful utility.
I'm sure it has helped many people safely mod their Wii!
Amongst other things it helped me create a blank emuNAND, and set it up on my Wii, which I'm sure I couldn’t have done without Modmiis help.
It's brilliant that it is still being updated and maintained by @XFlak so many thanks and Best Wishes to him!