romantics believed poets must be original by creating something new, instead of imitating or reworking classics

Poet means active.

Explanation:

Consider a drawing artist, drawings cannot be copied. If copied the creativity in art will vanish. In a similar way "Poets" need to be creative. Poets always imagine; they dream; they think something virtually; they go out of box.

The above factors are necessary to write a poem. A poet is a person who brings unreal, extraordinary aspects into the real world.

If the poet imitate or follow classic only, then it cannot attract young liker poem. So creativity takes the highest priority.