A materialistic outlook misses so much. As does an emphasis on concrete reality or causality.
How would you explain love, for starters? Much less admit passion? Why does music move us the way it does? And pain, be assured, is more than a neuro-chemical calculation. Why does social injustice to others spur our own anger? How could those who own all the creaturely comforts ever feel lonely?
The materialistic reaction to these, I suspect, prompts what we call addiction. Though it’s not always to alcohol, tobacco, illicit drugs, food, or even sex.
For liberation, a spiritual dimension will open. Or else.
Jnana's Red Barn 
Interesting. If you can’t imagine it, it can’t be? All those things have perfectly unspiritual explanations, and besides, materialism is not the only alternative to spirituality.
The plot thickens!
Reversing your statement, here we get: A spiritualistic outlook misses so much. As does an emphasis on abstract concepts or imaginations.
You ask “why” and “how” You are putting rhetoric before grammar and logic. Ask “what, who, when, and where” questions before “why and how” for a balance of both spirituality and materiality. These are not separate.
See trivium education for examples
https://en.wikipedia.org/wiki/Trivium
http://www.triviumeducation.com/
Learning to see what’s right in front of us is also considered a spiritual practice, one often called Awareness or Mindfulness.