It was only the advent of recorded music that allowed individual performers of popular music to gain specific audiences (with free jazz performers of 1930s being perhaps the first popular recording artists noted for producing "works of art").
So music as just a product, in ways, isn't by itself new or evil. Now one can take issue with the characteristics of our modern music.
For discussion of the history of pop music, I'd recommend
Elijah Wald's How the Beatles Destroyed Rock 'n' Roll
Have to disagree with you there. The most immediate counterexample that jumps to mind is Wagner. Hugely popular and audiences went to a Wagner opera not looking to merely be entertained but for the artistic merit of his works.
I'm sure someone with a background in musical history can cite many examples even further back, my point being, I think there's been a constant gradient of music For Dance vs. music For Art, I don't think it's fair to say that one or the other is in any way particularly novel. (Victorian era music, for example, was a wide spread including everything from operatic virtuosos, to public house performances for dancing)
To your other point however, I certainly agree that music as a product is not new, that concept dates back long past even the eras of our classical masters.
It's not really some simplistic generality. The larger point is audio reproduction and the increased production of commodities is what allowed the uniqueness of a kind of musician to be their selling point, once a musician was "selling himself/herself" rather than being a paid player.
I was hesitant to talk about Mozart/Bach/the other greats because I don't honestly have a deep understanding for how music was societally perceived back then/what the delineations were between pop/"high culture"/dance/"artistic" music (e.g. what the isomorphisms are to the modern day, if there even are any), whereas the earlier 1900's were not so far different from the parent's 1930s claim.
Classical music was pop for it's time. People danced, drank, and even had massive riots when a controversial composer came to town.
However if we really want to compare the most popular pieces of each time, we really can't look at the "art classical". Most "art classical" wasn't even the most popular back then, from what I gather (though occasionally an "art classical" composer did make a popular tune that became well known).
It's difficult to find "top sales" lists of the old sheet music songs (which is probably the best parallel to modern record charts), but one someone put together for the US (https://thetop100songsofalltime.com/top-100-songs-of-the-189...) has, for the link example of the 1890s, mostly popular short tunes (in the 1890s, "tin pan alley" style).
Of what I recognize (there's a lot of songs on this list that frankly seems to have disappeared over time), there's some that probably would be the dance of its time. I wouldn't say all I recognize is "music to dance to" mainly because there are definitely some ballads among the tunes, as well as some Sousa marches, and songs which are probably more "sing-alongs". I'm guessing that most of these songs aren't exactly "works of art" in the way the original poster intended. :) But they were light entertainment for the time (ala pop today), and that's fine. Modern pop music also has some ballads that do not necessarily function as dance music, too.
I think the biggest difference between music then and music now, is that the dominant way to make a living was to compose sheet music for other musicians to play. Recordings quite literally changed all of this.
http://mentalfloss.com/article/55247/3-dirty-songs-mozart
Chopin, for example, wrote 59 marzukas, which is music for a traditional Polish dance of the same name.
Beethoven wrote many dance songs, especially waltzes.
Albeniz, especially wrote music derived from traditional music. Suite Espanola is a wonderful exploration here.
https://en.m.wikipedia.org/wiki/Suite_Española_No._1,_Op._47
I could go all night on this topic, but the point is that, although we don't recognize the music as dance, it was to the people of that time.
The individual artist or producer which want's to have a number one song is not driven mainly by money. The drive is just wanting to be the best. And being the best in such a competitive field requires having a highly polished product.
I see I get some downvotes for saying this, none the less it's true. And I say this as an former full-time now hobby musician/songwriter myself.
Thats the problem. Why are we treating music like an industrial product? (The answer is money)