According to Nintendo, they have received further complaints from Brawl purchasers who claim their Wii system is unable to read their game disc properly. These people also claim they have had no such problems with any of their other games.
Nintendo has issued a statement regarding the problem and it apparently just has to do with everyday dust and debris building up into the Wii system's laser units. The reason this only affects Super Smash Bros. Brawl game discs and not others is because the game in question uses a dual layer DVD which is much more sensitive when it is being read by the laser lens.
Nintendo has reached back to that shared generational Nintendo Entertainment System experience - a game pak not working quite right and requiring a hard blow of air to clear away the dust - and recreated it for a new generation. Brilliant!