Wii Sports makes sense, but the rest are definitely on the account of homebrew. Wii's are easy and popular to hack, just look at GBAtemp. As for Street Fighter, my only assumption is because it's online and had somewhat of a limited release:
This Dreamcast port was re-released in Japan in 2000 as Street Fighter Zero 3: Saikyō-ryū Dōjō for Matching Service, which was released as a mail order title via Dreamcast Direct. The Matching Service version differs from the original due to the addition of an Online Versus Mode. (Wikipedia'd, derp)
Anyway, if I ever find myself in need of a new disc label, it's usually just as scratched and unuseable as the rest of the disc on account of someone not taking care of it. So, not much need for it and it can generally be asked for when the rare time comes about. I'm still for scanning and archiving rare games though, and if something is impossible to buy for a reasonable price (with profits going to the actual game company), then you might as well be able to download it and enjoy a bit of gaming history. Not exactly talking about Street Fighter here (or any Wii games for that matter).