I think it would be more reasonable to automatically do minimal padding based on the maximum digits in a matched album or file set.
That is a good idea, although I think some customers might prefer to control it.
I use track padding for file sorting. Am I missing something? Is it somehow useful to add three zeros to the track numbers of an album which contains only 1 digit track numbers?
its only useful in that you may wish to have consistent trackpadding throughout your collection rather than just within an album, so= if you have a single 100 tracks boxset then you may wish to use this throughout, but again I see your point.