I expanded the context simply because we live in a world where many people think that a number in a book has an equivalant on a webpage, or that the XREF ID (aka person ID) will remain consistant over the life of the record. This creates problems for people and software developers.
I personally believe that this numbering system has major advatages for small studies and that I may consider its use in cases were I'm developing an "ancestry only" tree for someone (i.e. who were my great-great grandparents?) similar to a "FAN CHART".
As an addition to the current set of numbering scheme, It would certantly be of value for Ancestry only reports but would most likely have to be turned off when used in books, since it has not value in decendent views and has limited use when showing siblings (and their spouses) of "direct line" ancestors.