Please do your research before making baseless assumptions, this isn't a personal preference but one of the emulator in question. RVZ is the format recommended by the developers of the emulator in question. You can read more here regarding the problems NKIT format has.
Downloading ROMs you do not physically own is illegal and not encouraged here on these forums.
Again, not the best format for that platform. Preferred format for Wii titles is WBFS files. See linked article for similar reasons as to avoid NKIT.
Not implying you can't do what you want within your own collection, only informing the community that moving forward your collection should ideally not be in that format according to the developers of that emulator for the reasons noted in the linked article.