Literally none of the features discussed in your post are desirable for users.
Nonsense. Most so-called responsive techniques were driven by user demand:
1. for the "real web" on mobile devices
2. for actually usable web pages on mobile devices
3. for high resolution displays with sharper text and more detailed images
4. for respectful and reliable behavior in varying network conditions
These sorts of demands have been so strong that they upset the entire mobile industry, destroying huge incumbent companies.
As far as specific features...
Device-pixel ratios are how users get sharper text—and now images—when their hardware allows it. The alternative is that either users see smaller and smaller content/UI, or they are stuck with low-resolution displays. Neither of those are desirable outcomes for users (and sales show pretty well that users prefer high-resolution).
Mime-type alternation allows:
- all users (rather than some) to view content—this is self-evidently desirable by users;
- some users to reduce bandwidth—this is self-evidently desirable by any user who is bandwidth-constrained (either in terms of speed of data cap).
Element queries allow UI elements to be reusable components, so that they always behave the same way under the same circumstances. This is fairly obviously desirable by everyone, as the alternative is to have things work in myriad ways depending on unrelated circumstances.
User-based settings for preferring faster downloads/reduced data consumption is obviously desirable. I can't for the life of me imagine how you could say it's not.
If you're hosting different versions, provider links to the versions and let the user choose.
Nothing is preventing a responsive site from doing just that, but still being smart about which (and how many) bits to send down the wire to a particular user.
Don't serve up different content to different browsers unless you absolutely have to (and when you absolutely have to, odds are your UI is terrible).
You seem to fundamentally misunderstand what responsive design is about. This is not about serving different content (at all) nor distinguishing between browsers (at all). It's about providing optimal rendering of the same content for different viewing/network conditions. Fundamentally, what is optimal for 2560x1440@1x is not optimal for 2560x1440@3x. What is optimal for LTE is not optimal for EDGE.