It might be surprising but about the most important issue in typesetting the amount of information is little. Most books about LaTeX are explaining what typography is, and why TeX is great but they do not question the difference between left-justification and fully justified text. One of the few exceptions were made in the Tex journal Tugboat [1].
Such a debate is more general than the common question how to realize a certain layout with Latex because fully justified text and typography are strongly connected:
quote “For centuries, book printing has applied justification to nearly all paragraphs” [2]
And yes the statement is correct, a short look into the history of typography will show exactly this preference. Not only documents generated with LaTeX are looking mostly the same, but all the academic books and journals since 300 years have the same standard layout. It contains of two columns which are typeset with justified text. This produces a perfect straight edge and is described by typographers as good typography. That means, the assumption is everything which is not fully justified is equal to low quality typography.
It is impossible to find pro or cons arguments here but what is possible instead is to describe the situation as it is. It is very hard to find books and journals which are typeset with flush left layout. For example, recent issues of the PLOS One journal is doing so. Plos one is a non-traditional digital only academic journal. And perhaps this gives a hint what the idea is. Fully justified text is a sign for printed traditional documents while flush left layout is typical for online only publication.
References
[1] Are justification and hyphenation good or bad for the reader? TUGboat, Volume 37 (2016), No. 2 First results, https://tug.org/TUGboat/tb37-2/tb116akhmadeeva.pdf
[2] Udo Wermuth: An attempt at ragged-right typesetting, TUGboat, Volume 41 (2020), No. 1, https://tug.org/TUGboat/tb41-1/tb127wermuth-ragged.pdf