I can only say what my understanding is – how this complies with the dhamma others may be kind enough to tell me, please.
Imagination is a way of exploring beyond conventional truths by letting the mind go wild, where it wants with little or no constraints.
Knowledge is information (data that has been processed in the mind) and the knowledge that we are interested in is that taught to us by the Buddha through the Dhamma. To get real value of this knowledge it need to penetrated deep within and be applied to this life.
Training rules help to purify the mind to allow us to see past knowledge to a point of understanding what is the ultimate truth taught by the Buddha. The training rules prepare us but realization has to come from within, normally through meditation.
Applying imagination to the Dhamma is likely to lead us away from truth under the influence of the hindrances; it is also likely to lead us to speculate on matter that Buddha has taught us not to bother with – at best will lead us to waste or time and effort.
We imagine that we are this body, this social status … that only lead to a continuation of the suffering as stated in the first noble truth. The knowledge that we have is that we are not self, I me. The deep understanding of this is what would allow us to escape from the cycle of birth, sickness, old age and death. It is hard to see how imagination and mindfulness could coexist.
So my belief is that knowledge is necessary, understanding more important and given the human condition imagination is dangerous.