There is some truth in the rare or underrated Nes games. I don't see a lot in the underrated nes games on the vc yet. There was more then one reason why Nintendo released Donkey Jr. Math besides being rare.
One of the reasons, I could think of for Donkey Kong Jr. Math in its first year was Nintendo wanted to give a game for back to school made for kids. There might might be wii owners that have young kids and are in grade school. Nintendo marketed the system for all ages. Nintendo marketed the system for all ages, so the kid facter is a possibility with Donkey Jr. Math. Teens or Adults aren't the only ones who would play vc games.
Another reason is Nintendo wanting to release more then one 'Edutainment' title' for the vc. I don't see Nintendo wanting to release Mario is missing and Donkey Kong Jr. Math in the same year or week. Most people wouldn't be pleased with Nintendo if Nintendo did that. Nintendo is doing for a "school theme" of games on the vc. Nintendo also has Mario Paint, a game that would interest kids or maybe teens. That game is made for the wii remote. Nintendo is only releasing the 'Edutainment' titles" during or the start of a school year. There are 3 'Edutainment' titles at least that could be released on the vc. That means 3 years of having 1 'Edutainment' title game.