No, it doesn't mean that you can go around and install every IOS without issues, in fact you can easily brick your Wii like this. Certain IOS, mostly in the multiple of ten (e.g. IOS60, IOS70, etc.), are utilized by certain system menus. Throughout system updates, when Nintendo pushes out new IOS files, old system menu IOS will be stubbed out (meaning it is rendered useless). If you install the latest of every IOS, you have a high chance of stubbing out your system menu, bricking your Wii in the process. Case in point, don't install everything. Keep what you have on the Wii, and update anything as necessary.