Why do they need a justification? English is under no obligation to imitate Latin plurals, and it adds no functional benefit.
Edit: interestingly, the title of the article uses the English, while the body uses the Latin (although in one case that’s because it’s from a name).
Edit2: Relatedly, I had a "shower thought" that even the most pedantic Latinophiles say "albums" instead of "alba". Although I also know a Latinophile who reluctantly used "alba" for a folder on his music app -- but that was only because "albums" was a reserved word.
I agree, it’s time we stop pushing words like “cacti” and just accept the inevitable English-ication of words and say “cactuses”.
This is a tangent to the article, but along these lines people love correcting “octopuses” as “octopi”, but “octopus” isn’t a Latin word, it’s Greek, so the “-i” ending isn’t correct.
"Virus" is also a word that frequently gets pluralized incorrectly, if you're thinking of it as a Latin word used in an English context. The only plural form that makes sense in English is "viruses," mostly because the Latin form actually has no plural. [0]
That doesn't stop people from writing "virii," however. Both "octopi [1]" and "virii" are examples of linguistic hypercorrection [2], in which a speaker misapplies a known linguistic rule that seems to fit, but does not. Neither of these examples are attested in the source language the word derives from; people literally use them just to sound smart, most of the time.
Other examples are using "whom" in places where the correct word would be "who," not using a preposition to end a sentence or clause with [3], and to not split infinitives [4].
[4]: My favorite origin theory for this one is basically "you couldn't do it in Latin, so don't do it in English." Early grammarians frequently took inspiration from Latin, because its grammar was already well-codified, mostly due to it being a dead-ish language. See https://en.wikipedia.org/wiki/Split_infinitive#The_argument_...
I think it’s fine to say or write -es or -I in general usage. I think it’s also fine to prefer one or the other in contextual usage. And I think it’s fair to roll ones eyes at people making a big deal of it.
But it’s incorrect to say octopus is not a Latin word. That’s like saying utensil isn’t a French word. It is, and it came to English from Latin through French. Octopus came to English through Latin from Greek. It’s a Latin word and it’s a Greek word.
So, I don’t think it’s a consistent position to be okay with the Englishification of Latin words, but not be okay at the Latinization of Greek ones!
Edit: interestingly, the title of the article uses the English, while the body uses the Latin (although in one case that’s because it’s from a name).
Edit2: Relatedly, I had a "shower thought" that even the most pedantic Latinophiles say "albums" instead of "alba". Although I also know a Latinophile who reluctantly used "alba" for a folder on his music app -- but that was only because "albums" was a reserved word.