The argument for in-text citation, which I agree with, is that an assertion is often only as good as its source, and that deflecting citations to the foot of the page seems to encourage the court to place less emphasis on the cited authority's weight and nature.

Similarly, I delight in footnotes that discuss how hard a point is to nail down, or that recite arguments pro and con. Walter Isaacson's bio of Einstein, which I'm reading now, has lots of endnotes like that, and to me it's unfortunate that seemingly factual assertions in the text are segregated from the issues raised in the notes.

Some people are bored by such things, but I don't think those are people worth catering to. Not all books are storybooks. An intelligent reader should be up to evaluating the sources and issues behind the text.

In an online format, I'd prefer footnotes to be hover-over pop-ups and citations to be hyperlinks.

Compare people who don't read reduced-type blockquotes; those aren't a distraction.

The UK academy strongly prefers parenthetical notes, though. So if it's a British book, there's just no getting around the interruptions.

I suspect that end-notes have become popular because they're so much easier to implement in modern word processing programs. They lead to cleaner and easier pagination of the main text and can be generated almost instantly once the text is completed. If there are substantial edits, then it still only takes a click or two to get the new end-notes pages all properly formatted.

With footnotes, you're always having to deal with odd and ugly page breaks after a major edit.

I like the combo of parenthetical and footnotes because the parenthetical citation lets me know as I am reading basically where the information came from and then a footnote lets me know that there is additional info below. If every citations is a footnote, having to look down at the bottom of the page for Smith, 23 is a waste of time and breaks up the reading. I can easily assimilate and dismiss, if needed, the basic citation.