Yes it would be good to get some clearer clarification on the updated rules.
In the App Store Review Guidelines it says:
"1.3 Apps in the Kids Category may not include third-party advertising or analytics."
In 5.1.4 it says "Apps intended for kids may not include third-party advertising or analytics."
As you say, "intended for kids" is vague, because thousands of games/apps aim themselves at kids but don't put themselves in the kids category because of the stricter rules. You need to be clear on this so that we know when an app is breaking the rules.
Another platform recently came out with a new policy, you have to apply your target audience upon submission. If reviewers think your app might appeal to kids but not specifically target them, and you don't follow the stricter rules, then parents will see a warning that this game isn't for kids. However this isn't on iOS yet.
So yes clarity on intended for kids in the rules needed.
The reason why so many kids apps exist outside of the kids category is that this rule isn't enforced:
2.3.8 Metadata should be appropriate for all audiences, so make sure your app and in-app purchase icons, screenshots, and previews adhere to a 4+ age rating even if your app is rated higher. For example, if your app is a game that includes violence, select images that don’t depict a gruesome death or a gun pointed at a specific character. Use of terms like “For Kids” and “For Children” in app metadata is reserved for the Kids Category. Remember to ensure your metadata, including app name and icons (small, large, Apple Watch app, alternate icons, etc.), are similar to avoid creating confusion.
If you search, there are thousands of apps using kids/children in title/subtitle/description and not in the kids category ♂
In response to your (3) above, you can remove apps from the "made for kids" category, the guidelines say: "Keep in mind that once customers expect your app to follow the Kids Category requirements, it will need to continue to meet these guidelines in subsequent updates, even if you decide to deselect the category."