Why is variety an outstanding characteristic of Victorian poetry?
Victorian poetry shows such variety for several reasons. Queen Victoria emphasized a return to a stricter morality, needed after the influx of rural laborers into London with an attendant rise in crime and poverty and immoral behavior. This correlated with the awakening sense of social outrage over social injustices to the poor and children. Victorian poetry emphasized both of these trends.
On the other hand, Tennyson (though not received well at first) emphasized a return to rich poetic language and imagery in reaction to the espoused natural language of the common pastoral person of the Romantic period and turned to a Medieval influence in his poetry. An adjacent movement called the Pre-Raphaelites embraced the same Medieval influences as seen in the work of Christina Rossetti.
Though subject matter might still revolve around romantic topics for Victorian poets, the romance was tinged with melancholy borne of the challenges to religious belief from of strange advances in scieces such as geography and Darwinianism. Robert Browning demonstrated the mix of romance and melancholy in his dark dramatic monologues.