[kazinator]

"-our" endings are a fairly recent British concoction based on French envy. (French spells it "couleur".) French probably has a good reason to write it that way because it captures the phonetics. The extra "u" does nothing in English other than take up space and ink.

The "color" spelling is: (1) shorter: absence of the superfluous is better than its presence; (2) etymologically correct, since the Latin original is "color"; (3) closer to the spelling of the word's cognate in a bunch of languages: Spanish: color; Basque: kolore; Italian: colore; Polish: kolor.

For at least these three reasons, it can be regarded as correct.

English dialects that use "our" endings and whatnot should rid themselves of the baggage, except in the case of direct French loanwords like "velour", pronounced "..oor".

[c22]

By the same reasoning I see you've incorrectly spelled superfluus.

[kazinator]

The reasoning is not the same at all.

Firstly, I'm not aware of a documented "superfluus" usage in English. Maybe we have to go back more than seven or eight hundred years to find it?

Secondly, "-ous" (like "-ose") functions generally as an adjective-forming suffix and is derived from the Latin "-ōsus"; it does not correspond to, and is not an expansion of the the "us" ending in "superfluus". "superflous" can be regarded as a derivation of "superfluus" that has been regularized with the "-ous" ending to make it recognizable as an adjective. This has happened with other words, like "continuus" and "contiguus". In contrast to these, many "-ous" words in fact some from ancient "-ōsus" counterparts, like "numerous" from "numerōsus".

The case for reviving "-ōsus" in English isn't very good; since neither of its "s"s are silent, it calls for a change in the actual spoken words, rather than merely spelling. Plus, it is unfamiliar to English speakers.

The case for creating a class of "-us" adjectives to restore Latin spellings like "contiguus" or "superfluus" is also not very good. It may be shorter, but adds to the proliferation of suffixes. To retain the pronunciations, we need "uu" to be rendered as the diphthong /yuə/ or /uə/, the precedent for which is scarce (being apparently limited to just "continuum"?) I'm not aware of any dialect of English in which such a restoration attempt has taken place, unlike "color" and "neighbor".

[c22]

Now you're applying different reasoning. You may be right, I don't speak latin.