The only reason I would mod my Wii is if homebrew was able to be used. I have 3 XBox's and the only thing I use them for is XBMC. If the Wii ever had XBMC ported over to it I would consider modding. Also, if Wii's online capability expands and you can't use it with a mod (same way your locked out of Live with a modchip) then I doubt I would do it.
As for using it to pirate games I wouldn't do that since I consider $60 every few months a good investment. I have been playing Zelda for over 20 hours and can easily say its well worth the $60 I spent, same with Wario.