I would say it's a matter of intent. It was your comment, so what was your true intent? Did you mean that people often think that blues is simple music (describing the music as simple)? Or did you mean that people often "label" blues music as "simple music"? I would say that your actual comment was ambiguous enough that only you know your true intent. Whether you were correct or not is completely up to you. Of course, we both know that you were wrong and it should be misconception. Why? Because that will you get you off the couch, yes?

"And yet" is no worse than "and then", "and so", "and still", etc., etc. In most cases, the "and" can be removed and the sentence is still clear, but that doesn't mean that the "and" is wrong or even redundant. In "and yet", yet usually means "in spite of". "And" means "in addition to". The two notions are different but not exclusive of each other, so if I want to describe a second occurrence that happens in spite of a first occurrence and also want to stress that the second occurrence happens in addition to the first one, then "and yet" is the perfect means.

@Warsaw Will, I agree with almost all that you said, except for one thing. You said that the original sentence is not very clear. I disagree. Every version put forth so far has a very specific meaning:

"I so appreciate you taking Gregg’s and my child to school today.”

can only mean that Greg and you have one child together and someone took him or her to school.

"I so appreciate you taking my and Gregg’s child to school today.”

can only mean the same thing. A few would say this is ungrammatical, with "my" coming first, but if not ungrammatical, it is at least considered rude by all. This pronoun shift is completely unacceptable, even in informal speech. If you talk like this, everyone, "educated" or not, will think you're a young teenager who can't put down their cellphone.

"I so appreciate you taking Gregg’s child and mine to school today.”

can only mean Greg has a child, you have a different child, and someone took both children to school.

"I so appreciate you taking mine and Gregg’s child to school today.”

can also only mean Greg has a child, you have a different child, and someone took both children to school. While this also may or may not be grammatical, it is still rude. See the comment above about "my".

If you and Greg had more than one child together, then the only way to say it would be

"I so appreciate you taking Gregg’s and my children to school today.”

Note, evey single one of these versions is completely unambiguous. Possibly all are grammatical, but some are to be avoided for reasons mentioned.

Last, Will, your comment about the need to mention Greg is very well taken. Specifically for cases where Greg and you have a child together, it would be extremely unlikely to mention Greg at all (which makes it even clearer that "mine" meaans two different kids). First, by mentioning Greg, it's at least implied that he's not actually present. If that was the case, why would he even be mentioned? You would simply say

"I so appreciate you taking my child to school today.”

Greg's siring would be completely irrelevant (but not ungrammatical). Perhaps that's why it would sound awkward.

Regarding:

"...as "adjective" as - is a comparison
so "adjective" as - does not make sense..."

and to all others who suggest that using "so" in the comparative, non-conditional sense is somehow wrong:

I disagree. I certainly do hear "...so big as...", ...so tall as...", "...so as..." etc.

I would suggest there is a subtle difference in meaning. Tolkien and Warsaw Will are on the right track here.

"He's not as successful as his sister" simply means the sister is more successful than the brother.

"He's not so successful as his sister" similarly means the sister is more successful than the brother, but also means that the sister is very successful. The "as" version implies nothing about whether either is particularly successful.

if "so" is less common, it's not necessarily because it's wrong; it may simply be because the difference in sentiment it conveys is not as often needed or intended.

I can venture a guess about defense and offense. The accent on the first syllable is typically reserved for sports references and often when "defense" is referring to the actual collection of players. I'm not much of a sports fan, but I have heard "DE'-FENSE', DE'-FENSE', DE'-FENSE'..." chanted at games. It just wouldn't be sonorous for a crowd of fans to chant "de-FENSE', de-FENSE', de-FENSE'...", would it?

Not quite the jovial mea culpa I was expecting, well, hoping for:)

Re: "Finally, what is it that makes you and those who think like you believe that you are correct and those who think otherwise wrong?"

Kettle, meet pot.

(sorry, I just couldn't resist:)

I'm surprised no one has offered an explanation as to why vacuum tubes are called valves. Well, it's because they behave just like valves. In a vacuum tube triode, a small voltage applied to the grid can control a large current flowing between anode and cathode. The current can be gated on and off, just like a valve. Even a two-terminal vacuum tube rectifier behaves like a simple valve, allowing current to flow only in one direction (just like the check valve in my sprinkler system).

"Affectatious" serves another useful purpose; it isn't ambiguous like "affected".

Hairy, spoken like a man who isn't old enough to have ever typed one on a mechanical typewriter:)