Get out of here. I really want to be pleasant to you but it's really hard for me to do so. I do love the music of the romantic era. Schubert's late works are some of my favorite works of any composer. But to claim that ONE ERA gave birth to the BEST composers is simply complete bs. In fact I believe that comparing eras in terms of one being better or worse than another is a completely subjective exercise. The music that is produced in a particular era is so much more than just a facility for expression of emotion or to facilitate progression in an academic field, music is also a reaction to society, culture, and events of the period.
Consider why so much of the difficult, broken, and confused music of the 20th century was written, this dive into modernism? Why did it happen? They are reactions to the industrialization of society and eventually World War One and World War Two. The bleak outlook of the early twentieth century seeped into art. Artists tried to communicate the complete chaos and terror and horror they saw through their work. Look in literature! T. S. Eliot, James Joyce. And then in the late forties and fifties! The beat generation, looking for an answer in wounded, lost pot-WAR America. Look in art! Duchamp, Picasso, Rothko. They could not relate in the same way as before after all the complete destruction of World War One and Two. Look at images of the concentration camps and the death camps, of the ruined cities in the wake of the war. Read the accounts of soldiers in World War I, look at the numbers of how many died. Read Wilfred Owen's poetry!
Now look at music. The second Viennese School. Messiaen's Quartet for the End of Time, composed in a CONCENTRATION CAMP during World War II. Benjamin Britten's work in Peter Grimes, showing the cruelty of post-war society (it is not just an analogy for being homosexual or a conscientious objector). Britten's work under all it's gorgeousness also showed the complete GRIND of the twentieth century. Gears that didn't quite fit together being forced to grind violently. The birth of the Avant-Garde. Ask yourself why European composers like Berio, Xenakis, Stockhausen, and Boulez were writing how they were. They were composing in POST-WAR EUROPE.
Then consider all the composers who worked under the shadow of the USSR. Shostakovitch, and later Part, etc. There was a reason they composed the way they did.
These were not emotionless composers, they were finding how to react in fragmented in the fragmented, lost world of the 20th century. Life was not the same anymore.
I implore you to read this poem by Yeats, The Second Coming:
Turning and turning in the widening gyre
The falcon cannot hear the falconer;
Things fall apart; the centre cannot hold;
Mere anarchy is loosed upon the world,
The blood-dimmed tide is loosed, and everywhere
The ceremony of innocence is drowned;
The best lack all conviction, while the worst
Are full of passionate intensity.
Surely some revelation is at hand; Surely the Second Coming is at hand. The Second Coming! Hardly are those words out When a vast image out of Spiritus Mundi Troubles my sight: somewhere in sands of the desert A shape with lion body and the head of a man, A gaze blank and pitiless as the sun, Is moving its slow thighs, while all about it Reel shadows of the indignant desert birds. The darkness drops again; but now I know That twenty centuries of stony sleep Were vexed to nightmare by a rocking cradle, And what rough beast, its hour come round at last, Slouches towards Bethlehem to be born?