I will write two spaces as long as Emacs has by-sentence navigation. I wouldn't care what anyone thinks about it.

I studied printing and typography in particular, as a student. I worked in printing and publishing, mostly in a large newspaper before I pivoted to programming. I haven't done any work in that area since the time Adobe Pagemaker overtook QuarkXPress (around the time of G5 and MacOS X). But, I think the principles are still valid to this day as nothing really changed in the printed text.

So, when paginating a newspaper, the goal is to achieve a "pleasant look". This includes a bunch of rules that... sort of have some justification sometimes, and less so other times... well, here are some examples:

* Don't allow for four consecutive lines to end with hyphens because it breaks the visual image of the body of text as a rectangle (or whatever other shape that the text was intended to flow in). Obviously, four here is a heuristic, and in reality will depend on the space between lines, the size of the font etc. But, the rule says "four".

* Similarly, don't allow for four consecutive lines to have spaces between words align vertically because it creates an artifact in the otherwise uniform rectangle filled by text.

* Don't allow for a single line from the previous paragraph to start a page / a column because readers want a paragraph to be close together as it's supposed to convey a single thought.

And there are many, many more, including the size of dashes that should be used in specifying year or time spans, used in math formulas as minus, used in direct speech, used as way to separate sub-sentences and so on. Unfortunately, these also vary by language and country. Sometimes even the prose vs verse will affect the preferred length of dashes.

So, when it comes to periods, they can happen in acronyms, in initials or to signal the end of the sentence. When they are used in acronyms or, and especially in initials / titles, it's very desirable to keep the word following the period with the space on the same line with whatever preceded the period. I.e. "V. I. Lenin" should be treated as a single word, from typographical perspective. In practice, in typography, there are "unbreakable" symbols, mostly dashes and spaces, and these would be used for titles and initials to prevent accidental linebreak from cutting through someone's name. In contrast to this, it's highly desirable that the linebreak occurs where the sentence ends.

Since keyboards offer limited input capabilities when it comes to text formatting, and in order to help editors to present text in a more easily digestible way, it seems like putting two spaces after a period, if it's meant to terminate a sentence is a small price to pay.

My typical way of working with prose in Emacs is that I repeatedly ask it to re-flow the paragraph (because of the edits I make to it). So, on top of being able to skip number of whole sentences in any direction, I would also prefer that the editor doesn't break initials off the name, while try to break lines on sentence end.

Most computer users today use crippled text editors s.a. VSCode or MS Word, which don't offer similar functionality, and so to their users double space after period would appear as a meaningless chore. I understand that the needs of the majority is where it will end in the end of the day, but, personally, will never accept this kind of approach.