There is certainly a trade-off between convenience of access and simplicity of appearance in deciding whether to place notes on the page or at the end of the book – especially if the book started life as a non-academic text and explanatory notes have been added later. In the early days of phototypesetting, when pages were made up by hand using (literally) cut and paste, footnotes became an additional cost, and were avoided where possible by many publishers. Large-scale, automated page make-up systems such as Miles and Penta made the position of notes irrelevant, as the pagination process could deal with foot-of-page, end-of-chapter, or end-of-book notes equally well; but these systems could not compete on cost with simpler Mac-based applications such as Quark XPress, which had nothing like the functionality. Footnotes in XPress used to be a real pain.
InDesign’s relatively competent handling of footnotes means that there is no reason for foot-of-page notes to be avoided any more, but I wonder if there is still a folk-memory that footnotes are ‘difficult’? I was pleased to see that some readers are still in favour of footnotes, as evidenced by this blog – but note the rueful ‘I guess footnotes have been done away with in this day and age’, as if publishers have persuaded readers that ‘there’s no call for them now, sir.’