first and foremost, the article only discussed the sales of famous, high-volume-selling artists. neither they nor i have the data to verify this, but i would be willing to bet that the distribution of album sales across all bands has flattened out significantly since itunes came about. i like itunes because i can find new artists on it through recommendations, search, podcasts... and if i sample an album's tracks and find it to be all good, i do buy all of it. but otherwise... why should i pay for tracks that i don't want to listen to? if an artist is arguing that the album is designed to be heard as a whole, then by all means, prove it.
secondly, again although it's the WSJ, i don't think it would have been too audacious to admit that perhaps half of those full albums aren't worth buying, and that popular music was going through a bubble thanks to the dominance of cd-based albums as the only medium around. to me, online music piracy emerged as a reaction to this. i imagine that fileswapping services still have a healthy user base, but the emergence of itunes from nothing to the dominant player in 5 years indicates to me that people are willing to pay for music, when they feel like they're actually getting something for their dollar. purely anecdotally, everyone i know who was a one-time "pirate" has switched to itunes/rhapsody. not because we're hugely wealthy, but perhaps because we're discovering more great artists this way, and feel inclined to give them some dollars to help them keep making music.