I treat Javascript as an embellishment. I try to think of sites as electric stairs that still work even when they are turned off. A site should be as accessible as possible.
The impact of having a site work without JS depends on who your site targets - if your site is mostly focused on young US professionals in cities using Macbooks and iPhones, bandwidth and browser support is going to be good enough with or without JS; you might lose out on some market share from accessibility if your site is poorly accessible, but it’s unlikely to be make or break for your site.
If your site is supporting elderly people in developing nations on low-specced computers/phones, probably a website isn’t even the best vehicle for your product, but supporting no-JS might be more significant for accessibility and bandwidth reasons.
I suspect the vast majority of products people work on here would not gain much by working without JS, although some passionate and outspoken people make it seem otherwise.
There's a lot of pie in the sky JavaScript discussion where folks talk about going without / this site doesn't need JS and so forth and I imagine they're talking about sites largely with static content and text where the user just consumes that and doesn't interact much beyond navigation.
I think those are valid points to some extent... and I'm not sure how many sites really are purely static no matter how much we might wish they were. I admit I miss that internet too but ...
On the other hand I work on a lot of 'web applications' for businesses... zero JS is not really an option.
As for how many people care overall about a lack of JS on a page, I'm pretty sure it is very small.
It's just another tool to create better interactivity in a page.
Just like CSS is a tool to create prettier pages. And HTML is an tool to create layouts and links.
I do think JS should be treated like a permission though. Just like asking for camera access... but apparently the JS sandbox is completely isolated so that's not at all necessary...