From an interview with The Guardian:
Keith Stuart: A lot of the young people who will listen to the Destiny song probably consume music through services like Spotify – they don’t buy albums anymore, they download tracks. What do you think about that? I mean, my sons will probably never hear the last four tracks of Abbey Road in the correct way – unless I force them to listen to my record collection.
Paul McCartney: Yeah, I do think about that. In an ideal world, they listen to what you’ve recorded in the way that you have presented it. But it’s their choice. If they want to read a novel and not finish it, that’s their choice, not mine. I’d just be pleased they were reading it. It’s all changed so drastically.
A lot of kids listen to music on their smartphones through these tiny little speakers. I’m pulling my hair out thinking, “Argh, I spent hours making that high-fidelity sound! Get a decent set of headphones! Please!”
Stuart: They don’t seem to care about sound quality these days, Paul.
McCartney: They don’t, do they? My grandkids don’t. But then the tiniest little noise can be exciting. Things change. Maybe when they get older, they’ll get into vinyl and become more sophisticated. But for me, at least they’re hearing what I’m doing, in some form or another. I mean, I’ve come through vinyl, tape cassettes, CDs, digital downloads … all along, the constant was that a song is required. The delivery system isn’t important. For me, I’d love people to be listening to the music in the most perfect way, so they can experience exactly what we made in the studio. But then it’s the difference between looking at a painting in a gallery and looking at a postcard of it – there’s still something good about that postcard.