I would think a typical user would want to either turn WiFi off or completely disconnect from their current connection (the equivalent of "forget this network" in settings). This temporary disconnection is baffling. You can turn it off, but it automatically reconnects the next day or when you move around.
I've got a feeling the carriers talked Apple into this. My phone will connect to an AT&T WiFi connection anywhere, anytime without asking my permission which helps relieve cellular network congestion in urban areas.
You have a distinctly minority view. The vast majority of times, and yes Apple has massive research to back it up, is that I and most people want to disconnect a device from the wireless; I don't want to turn it off completely, e.g., Apple Watch, Pencil, or just iPhone users that want to switch from one speaker to another or different headphones, etc. Apple's approach is designed to make it simple for what most people want, but EFF brings up a good point and Apple should give prompt when disconnecting from control center as to your intent or allow users to set default in settings as either off completely or simply disconnect.