I'd challenge the idea that off/passive really is the "normal" mode, from the ordinary user's POV or Apple's POV. The headphones just don't sound good in this configuration, with neither the background nor the audio sounding clear. They aren't engineered to give good sound isolation OR good background pass-through without active support, and until this post, I didn't even realize that the active modes use more battery life.
The messaging to users is also unclear. Without understanding how ANC works, what does "off" actually mean? It's not turning off the audio playback, and it's not turning off the background noise. It IS however turning off the (newly-advertised) active features like Loud Sound Reduction, which users would expect to be working whenever they are wearing the headphones (or at minimum, whenever music is playing).
In typical Apple style, it makes perfect sense for "off" to be treated as an advanced feature; the problem is that they already shipped it a long time ago, and then removed it without any explanation.