Actually, the state of our minds, sort to speak, with imaginations, is our fallen state. Yes, beautiful icons are done, but that's because of focusing on prayer towards God. Mostly, our spiritual focus is nil and distracted by non-God stuff which gets muddled with all kinds of imaginings.
Adam and Eve didn't need imagination as they were living with direct communication with God in mind, body and soul. They were healthy in the right way (until the Fall). But, WE are pretty messed up. Like everything else, we sinners take God's gifts and pervert them, whether it be through the mind, body or soul.
Even if we think our imagination is righteous like wondering what it was like to see Jesus Christ walking amongst the people, it is a thought of self, even if we don't see it. What the ascetic saint in the desert showed was the extreme form of focusing ALL towards God. Their minds were cleansed and free.
Did you know that having dreams is the sign that we are spiritually ill? It's a disconnect from God. But, the saints didn't have dreams only direct visions from God, if it was while they were sleeping.