I don't know why this seems like such an imposition, but I think I'd be uncomfortable with my browser exposing information about my actual network if it didn't have to. I have a feeling way more people would be using this to track me than to considerately send me less data.
That said, browser buy-in could be a huge help, if only to add a low-tech button saying, "request the low-fi version of everything if available." This would help mobile users too -- even if you have lots of bandwidth, maybe you want to conserve.
Indeed; as an user, I don't want the site to decide what quality to serve me based on probing my device. It'll only lead to the usual abuse. I want to specify I want a "lightweight" version or "full experience" version, and have the page deliver an appropriate one on demand.
I remember when websites used to have "[fast internet]" or "[slow internet]" buttons that you could use to choose if you wanted flash or not. Even though I had a high-speed, I chose slow because the site would load faster.
It doesn't have to be your actual bandwidth. The values could be (1) high quality/bandwidth, (2) low quality/bandwidth, (3) average. The browser can determine that automatically with an option to set it if you want to (e.g. for mobile connections).
That should solve most problems without giving away too much information. But an extra button would probably just confuse people.
Progressive resources would help a lot here. We have progressive JPEGs and (I might be wrong) PNGs, you can set your UA to low-fi mode and it will only download the first layer of the JPEG.
If you consider every identifying piece of information as a bit in a fingerprint, it makes more than a significant difference; it makes an exponential difference. Consider the difference between 7 bits (128 uniques) and 8 bits (256 uniques) and then 15 bits (32K uniques) and 16 bits (65K uniques). Every additional bit makes a difference when fingerprinting a browser.
This sounds just like the idea that the website should be able to know how much power you had left on your device, so it could serve a lighter version of the webpage.
I think the arguments against are pretty much the same.
I don't know why this seems like such an imposition, but I think I'd be uncomfortable with my browser exposing information about my actual network if it didn't have to. I have a feeling way more people would be using this to track me than to considerately send me less data.
That said, browser buy-in could be a huge help, if only to add a low-tech button saying, "request the low-fi version of everything if available." This would help mobile users too -- even if you have lots of bandwidth, maybe you want to conserve.