I wouldn’t go that far, gex gex, but I have wondered the same thing myself about much of the music that is played today: and that includes country. How much of it will be popular in 15-30 years?
The reason I wonder this is not so much believing that my style of music is preferable or obviously superior, because I listen to a lot of stuff from many different eras. (Yesterday I was humming “Minnie the Moocher” at work. The day before that, “Misty.”) No, the reason I feel that way is that a certain amount of modern so-called urban music is topical and current. Some of it deals with the current way of life for its singers, its listeners. Some current country tunes are topical, as are even some rock tunes. I note that “Born in the USA” isn’t played as much as, say, “Dancing in the Dark,” because one addresses the bleak future of the post-war Vietnam vets in a hostile and depressed economy, and the other with a guy and a girl. Will Lee Greenwood’s post-9/11 work be on a radio station in 10 years? Will the Princess Di version of “Candle in the Wind” survive long?
More to the point of the older music, because I used to work in a piano and organ store playing oldies for our primary buying audience, while we remember “Hello My Baby” from circia 1910, we don’t remember “In The Baggage Car Ahead” because its subject matter is no longer applicable. We don’t travel as much by train (or listen to waltzes, but that’s another story too). We remember “Cherry Pink And Apple Blossom White” or “Moonlight Sonata,” from the WWII era, but not “Don’t Go Sitting Under the Apple Tree With Anyone Else But Me.” How about Europe’s “The Final Countdown?” Who even remembers what the title of “Pennsylvania 6-5000” means (and when we switch to ten-digit telephone numbers, what about “867-5309 (Jenny)”?) Who knows half of the references in Paul Simon’s “A Simple Desultory Phillipic (Or How I was Robert MacNamara’d into Submission)”? When will Billy Joel’s “We Didn’t Start The Fire” be completely forgotten?
Anyway, back to the OP, I do believe many people find instrumental-only music to be difficult to listen to. My guess is, they never learned how to listen to it, or what to listen to. Most pop, rock, and other verse-chorus-verse-chorus-bridge-verse-chorus music is nicely predictable and has a narrow range of chords and tones and generally one tempo throughout. (This doesn’t explain why “Stairway to Heaven” and “Bohemian Rhapsody” are so popular, though.) Perhaps they just feel a tighter emotional connection to a song that says something (literally, in words) that they, the listener, want to be told. Many of the songs and bands of the era strive to capture the essence of growing up and the issues of the day: it’s so tough growing up, I’m so afraid of this, I really enjoy that, nobody understands me, how cool am I?, etc. Popular music – stuff with lyrics – talks to its listeners and reaffirms and explains how they already feel.
Well, that’s just a lot of blather, anyhow, but that’s what I think. You’re free to disagree or say I’m way off base. 
FISH