I can understand Pink Floyd's objection to selling by the track (at least partially). With The Wall, "Comfortably Numb" is the only song on the entire double-album that does not segue in from the previous or out to the following song. In fact, even "Outside the Wall" segues into "In the Flesh" with the phrase "Isn't this where we came in?" split between the two, which made for a continuous loop of the album in 8-track form.
I have a few songs that I have edited for play on my MP3 player so that songs that are usually played together are combined so that I can listen on shuffle (such as "Brain Damage / Eclipse", "Long Distance Runaround / The Fish", and "Heartbreaker / Living Loving Maid" (though Led Zeppelin denies those songs are meant to be together, the lyrics indicates otherwise)).