I often look at the kanji training as being similar to learning how to spell and having weekly spelling tests, which is something that I’m not sure is still done in the States.
I could really benefit from studying the kanji with my kids, too. Like you, I can read a lot of characters, but when it comes to writing them, forget it.
It's funny you mention that. A dozen or so years ago, I remember proposing the idea that since spelling is so divorced from pronunciation in modern English, memorizing the spelling of words is little different from memorizing the stroke order of kanji, making kanji and English spelling very similar. I got a lot of flak for that idea, but I still think it's true. I was never very good at spelling...
I’ll stand in your corner if you ever want to have that debate with somebody. 😉
I think adding the fact that spellings change within the English language depending on the country your from, while it might not strengthen your argument, could help you further your position that spelling is very separated from pronunciation.