Do you agree that the darkness, pessimism, and negativity are the focus of "The Darkling Thrush?"
Well, I would say that a major focus in Thomas Hardy's poem "The Darkling Thrush" is joy. Amid the misery, cold and damp of a British winter at the dying of the century, a cold, aged little bird sings out for pure joy, giving us all hope for the future. Certainly, Thomas Hardy himself had much pessimism, depression and sadness in his life. He lost dear friends through bereavement in tragic and horrific circumstances. he was also (like many Victorians) worried about the end of the century, with menacing political rumblings coming from Europe and social change. Yet, in life, no matter how hard, there is usually some joy somewhere and this is is often most simply found in Nature. He uses words like "darkling" and "spectre-grey" to emphasise the gloomy mood in country and society.
I think that there is no question that much of the poem does focus on darkness, pessimism and negativity. But I would say that there is more to it than that -- I, at least, see some hope as well.
Clearly, there is a lot of pessimism here. The first two stanzas are completely bleak with their talk of death and winter and broken lyre strings.
But then the last two stanzas offer some amount hope, even though the lines are not totally optimistic. The speaker does admit that there is a possibility that there is something out there worth singing about.