The rule about two spaces after a period is still in play if you are working with a monospaced typeface such as courier or consolas. The editor was working in Times Roman, so even if you put in the spaces, the word processor would tend to undo your work. Also, in the book publishing business, we don’t have rge luxury of indulging in personal preferences, especially if the work winds up going ti typesetting who would have yo undo it all in QuarkXpress.
Good technical (and technically correct!) response. And HTML gets rid of extra spaces, so I’m basically screwed online.