I need to ask why UK English says "colour" and US English says "color". And lots of other examples like that.
The answer, I think, has something to do with the way that we view language. It seems to me that US English is more orderly, more rules based, more logical. By contrast, UK English tends to be more organic and chaotic.
I'm a UK English speaker. I have lived in England all my life. When I see the word "colour", I know it is pronounced "culler". But I think a US English user would look at "colour" and expect it to rhyme with "sour" or "flour". By the application of the rules, US English expects every group of letters to have a consistent pronunciation.
By contrast, UK English works on historical precedent. I know that "colour" is pronounced "culler" because I've memorised it from an early age. It just is.
The classic example is the word "lieutenant". In UK English, this is pronounced "leftenant". I have no idea why, but that's just how it is. Interestingly, this particular word is starting to change. Younger generations of UK English users are starting to say "lootenant". One of the side effects of a language based on historical precedent is that meanings and pronunciations can change.
I watched a Sesame Street programme once which talked about "in front of" and "in back of". To a UK English speaker, the phrase "in back of" sounds funny. We just would not say it. But I imagine that a US English speaker would reason that we say "in front of" so we must also be able to say "in back of".
You can see this difference of approach in the posts in the grammar forum. US English speakers tend to be far hotter on "correct" grammar, where UK English speakers will sometimes concentrate more on how a word is used in real life.
Before anyone starts to get annoyed by this, I ought to say that neither approach is right or wrong. It's just a subtle difference in the way that language is used. I once heard a lecturer say that it might have something to do with the different histories of the US and the UK. The UK has been invaded so many times that we have become quite used to an organic and shifting language. But the US was a new continent which where there was a chance to impose order from day one.
Noah Webster changed the spellings on purpose to "Americanize" them, saying stuff about the English aristocracy having corrupted spelling and grammar and such. Most of his changes caught on, and that's why we spell stuff different. (Not all of them. Apparently he wanted to make tongue into tung and nobody liked it.)
I (an American) don't think colour is supposed to rhyme with flour, in the same way that I know through doesn't rhyme with trough and neither rhyme with though. I also know that wound, the past tense of wind, is pronounced differently than wound, the noun, (and wind the verb different from wind the noun) because I'm a native speaker and I just do. We learn these things--spelling doesn't always make sense, you just have to know. Colour is color, but one looks weird.
So I do think there is truth to what you're saying. People did want to distance themselves from the British on purpose upon their independence, so we made a tremendous declaration of our freedom by spelling things different.
But we can have some very fluid grammar, too. I think the first lines of a Nelly song go something like
C'mere girl
Who your name is
Where you from, turn around, who you came with
Is that your ass or your momma half-reindeer
Can't explain it but damn sure glad you came hurr (is this spelled "Herre"? I believe it is either "hurr" or "herre" when said in this particular dialect
)
'n' stuff.
So, I dunno. But it is interesting, what you say, good sir or madam. I think maybe at the outset we did have this purposeful "let us revamp language to have it make sense" thing going on, but more recently it has taken on a less rigid life and gone off in some different directions.
I don't know anyone under the age of thirty in the UK who was taught rigorous, proper grammar in public education unless they elected to take English Language at A-level, myself included. It's just not been on the curriculum.
I'm pretty sure most Americans don't get "rigorous, proper" grammar either.
I didn't, anyway. Some, but not rigorous. I learned a lot more from reading in general than from lessons in school.