As we're talking about The Missingno Tracks then it's already been explained. The project has been in the works so long, with so many different remixers and various project leaders, that mixers weren't around to supply a .WAV or project files were lost or even deleted, various things. Rather than simply release an MP3 version and get all kinds of "cut me some FLAC bro wtf i wan lossless" and have to explain WHY not all the tracks have FLACs case by case, it was easier just to bundle it all together with a choice.
As for the corruption thing, all the tracks have been fine on my machine.
As for the incorrect version thing, said two versions were incredibly similar. He posted some mp3s as WIPs then the final thing in .WAV. Don't tell me it's not stupidly easy to think "oh, that MUST be the one I converted to mp3" after a quick listen.
Yes okay, things messed up. Remember that this isn't a bunch of guys in the same room, heck even the same city, it's a project arranged and sorted from all over the world.