It was covered on MacRumors front page when iOS 11 came out.
Apple's reasoning is that often you just want to disconnect from currently connected devices such as BT Speaker or Headphones, but still have access to Apple services such as Handoff, Car Play, Apple Watch, Apple Pencil.
Likewise with WiFi, that you want to disconnect from the WiFi network your on, but not necesserily needing to turn all WiFi services off, so things like iPhone instant hotspot can still work.
Whether you agree or not, but it was a conscious choice. As long as users are aware what the toggle does and doesn't do it shouldn't been seen as a mountain but a molehill .... But forums being forums