I don't see that it'd be that hard, could just display applicable levels based on equipped tools or weapons. However I wouldn't exactly consider this a priority request. :p
hmm. When I'm carrying a pick, I've an option of 5 skills to use that are specific to that tool.
Or I can cast spells (albeit slowly) with it, wich potentially also give exp, thus adding another 4 for a total of 9 skills that would have to be tracked for just that tool.
A craft tool is similar. In the extreme, an armour crafting tool can be used to make 18 different items, for 18 different skills. Add those same 4 magic skills, and that's 22 skills that would have to be displayed when using that tool.
There goes triviality :)