In my opinion, being able to just legally download single songs (and any song, not just the songs released as singles) is one of the best things to happen to the music industry. That way people who only want one song can just buy only one song; the consumer pays for it, the artist and the label get payed, the consumer doesn't get sued into oblivion, and the consumer doesn't have to buy the full album unless they decide to make that commitment at a later date. I remember back before downloading music (even before the original Napster) when you had to go out and buy the whole album even if you only wanted one or two songs. Because of this, you were always much more restricted to how many bands you could actually "get into" at any given time because you had to pay $20 per cd. Now, if someone hears Pull Me Under and they decide that they like it, they can just download that song, and pay for it, and maybe later, they will buy the full album, go to concerts, buy merch, etc etc. Allowing the consumer the option of spending less per band helps them to broaden their musical palette because they can sample a whole bunch of artists rather then having to buy only one album at a time.
Now don't get me wrong. I love albums, especially albums by bands that actually know how to make full albums, not just a few singles and a bunch of filler. And I do feel that concept albums and rock operas in particular can only be fully appreciated by listening to them as a whole. Many of my favorite albums by many of my favorite bands are concept albums or rock operas (specifically, V by Symphony X and Streets and Dead Winter Dead by Savatage; oddly, Scenes from a Memory is not my favorite DT album, but I digress). But forcing people to buy only full albums kind of defeats the purpose of buying songs via download. If I had to buy the full album regardless of the medium, I would just go out and buy the physical thing (which I usually do anyways for bands I really like). At least that way I own the physical record.
So is this whole thing about Pink Floyd wanting special treatment just because most of their records are concept albums? That seems awfully pretentious of them, and it opens the door for other artists to start making these demands too. Who will be the next to claim this sort of special treatment? David Bowie? Marilyn Manson? Trans-Siberian Orchestra? Many artists do "concept" albums on a regular basis, and the whole definition of what makes a concept album is rather vague anyways. Many albums have common themes and motifs running through them; that doesn't make them concept albums. Before you know it, Miley Cyrus will be demanding the same thing because the lyrics to pretty much all her songs revolve around certain themes (read: teen life shit) and therefore her records should be considered concept albums too!
Honestly, there is a part of me that thinks this really is just about the money and they're just using the whole "artistic" thing as a moderately respectable justification. If they really did not want their songs listened to out of context of their respective albums, then why would they have "best of" compilations? I don't hear Floyd bitching about how all the songs on Echos are being "taken out of context". No, this is all about forcing people to buy the whole album, rather then letting people just buy a track or two to get a taste, and then maybe come back for more to make a full album commitment.