The way I see it, we can think of the screen below the notch as actual display area and consider the area next to notch as bonus display dedicated for menubar. The bonus area goes dark when in fullscreen app. So, the app area is consistent in both modes.

This way you don't have to feel like there's wasted space.

Is there a chance anything that us paid attention to grows in size.

Would anyone be willing to go to an older laptop without it?

Assuming not, what are the options? External displays?

I find I usually look at the content on the screen not the webcam or the notch, but it could be different for others

IIRC, Apple used to have the ambient light sensor under the left speaker grille. If you happened to rest your hand there, it would make your screen suddenly start dimming.

When using the laptop in a dark environment, it was also prone to a feedback loop where the screen dimming would result in less light hitting the sensor, leading to further screen dimming, or runaway brightening. Putting the sensor facing outward from the plane of the screen minimizes that feedback.

How can you not notice that? Hate it or not it is incredibly easy to notice.

Same here. I actually had to look up whether my model had it since I'm not in front of it.

I do use external screens a lot tho (in addition to the built in one).