A few fair points, but ultimately I have to disagree.
Yes, it is a matter of habit and comfort... if you're used to double spaced sentences, you're going to prefer them. But that does not dictate on whether it is better or worse. After all, it's only in the 19th century that that was a practice -- readers before and after were fine with single spaced sentences. Similarly, because of practices in academia, many people are more comfortable reading double spaced lines of text, but surely that does not make for better typography.
As I said, I'm in the camp of De Vinne and Knuth.
Of course, De Vinne was part of the generation that introduced the doubled spaced sentence, so I don't think it's a very strong argument to bring him up. Most modern typographers don't support that view. And to be fair, we're only talking about the space between sentences here, not the use of blank space in general. That's a whole art form in itself. Still, excess is its own counterargument; to need blank spaces is one thing, but how much is an entirely different argument. Excess of blank space stands out, and may distract the reader from the text (the important part)
As for Knuth, what he did was a godsend for digital typesetting, but it's important to remember he was NOT a typographer. He was a product of early 20th century education. Plus, I don't think LaTeX defaults to a double space (though I'm not 100% sure).
the hordes of typography experts who are telling us that two spaces after final punctuation is bad and should not be used have no purely factual nor logical reason for this.
Not true. The reason is entirely logical. So logical that it devolves to minimalism: do what you must but avoid excesses. The one space and the capital letter that follows it is enough of a visual queue to denote the separation of the two sentences. The extra white spaces would be superfluous.
It's entirely a matter of "looking good," and of course that will always come down to taste.
Again, not a fair point since most typographers and typesetters are paid to make texts legible, not make them pretty. For any typographer that's worth their pay, legibility is their first priority.
In the end, however, it's really not a make-or-break issue. It's one of the finer points (still, very fun to argue about it

). I'm very much in favor of the single space, but no text has every bothered me for having two spaces after punctuation.
I'm curious though: given your admiration of Knuth, why didn't you use something like LaTeX to typeset BFRPG? It is free and open source, just like LibreOffice.