I want this, and although there isn’t always a perceptible difference in audio quality, there sometimes can be. It depends on the content, and I’d rather sometimes stream audio at an excessively high bitrate than always lose the high–end definition that I could have enjoyed where it exists.
All my life I’ve been getting into disagreements with people who believe that because they can’t tell the difference between A and B, I must not be able to either. I find this immensely frustrating.
At that point where it matters, I feel like I should be buying the music from the artist, not streaming. My latest favorite band, Mad Routine, gives you the WAV masters when you buy their albums, and they are meticulous about sound; those lossless tracks actually sound better, even with Bluetooth.
However, I think few bands are actually putting in the effort to have beautifully crafted lossless tracks. Also, I have no way of knowing if Spotify is merely increasing the bitrate but using the same lossy source file, which is what I suspect is probably the case. After all, why share valuable goods when you could pretend and throw out a few buzzwords, instead?