Yes, agree with pretty much all that. I would tend not to be too dismissive of the value of learning the principles of coding. At my daughter's age, the concepts of IF/THEN constructs and all the other coding principles are all very new and worthwhile I think. And primarily at this stage, I think my aim is just to get her enthusiastic about learning, so the scratch level programs have been great and she still has some way to run with it. However, I take your point that she will pretty quickly run out of runway to learn with just coding which is why I am already thinking about what next.
Your point about teachers asking what will you drop is very valid. They don't teach this stuff in normal school time for that very reason. However, as a parent I have oodles of after school time and holidays to fill which I would like to be as enriching as possible, hence my interest in this. I'm not actually particularly focused on coding or even STEM. However, I did attend a DATA 61 event where one of the keynote speakers was 9 years old and was a little blown away by the potential of young people to create a future using data. As you say, its what you do with the data rather than coding as a skill that will make the difference. However, I think understanding how to manipulate data via coding will be \ a modern day skill that should sit alongside other skills like literacy and mathematics. But how to develop it over time in a reasonable fashion?
I put up a proposal in EA about a year ago to launch a STEM Outreach Community, whereby deliverers of STEM education services such as yourself could collaborate and learn from each other. It hasn't got traction yet but I remain hopeful.