I'd agree that in general you can't tell the difference between a well encoded MP3 and FLAC, but there are songs in which it makes a difference! To test myself I've run a few simple ABX tests; I'd encourage to try it out! It's worth noting that this is only at home with a DAC/amplifier and some decent headphones, but if I'm out and about then I have no qualms about streaming.
My collection of music is all wav/aiff or 320kbps mp3. I'd love to say I can tell the difference, but I can't.
It's not just about being able to tell the difference. Remixing is another example of things that require losslessness. Archiving as well.
Perhaps. However my contention is that if am paying the same price for supposedly an 'identical' product, then make sure it's actually identical.
At least ebooks generally are a tad cheaper than paperbacks, even if not by much, but not MP3s? Why? Simply because they can get away with it, I suppose.
So it's a format that takes tons of disk space for no perceptible benefit. Why would it be popular? It's a niche format for niche uses.