Because Torah is our Book of Life, an eternal source of instruction, that question, rather than being a mere historic anectode, is a question always being asked of Man. Over time, man finds himself, hopefully, advancing in life with a meaningful purpose, and every time he should consider the question G-d asks him - to see if in fact his answer indicates he's made real progress.
Perhaps many of us don't lose much sleep over our spiritual shortcomings, as much as we do over our materialistic shortcomings. Thus, the question of G-d, as it reverberates continually when we think of it, should shake us out of our spritual complacency - because that's where that question points to: Where does our soul stand today compared to where it stood yesterday?
G-d expects of us to move forward, to toil to achieve more - not more money, not a better job, not a better physique, not more respect, power or honor. He wants us to become better Jews as Torah beseeches us. After all, we were born with relatively empty vessels, and the world was created purposely with imperfections. Our souls were given this mission down here on earth, to enable the future world for divine revelation. By elevating ourselves spritually, we force a physical change in the world that improves it and raises it a notch; A real cause an effect reaction.
Adam was told, "Don't eat from that one tree!" There were hundreds of trees, and thousands of fruits to eat from in the Garden of Eden. What would it harm the world if one fig, or date, or grape, whatever tree it was, were eaten? What damage could consuming one little fruit wreak on the world?
Well now we know. That tiny act changed the world drastically. Death came to Mankind. Truth and falsehood no longer were clearly delineated. Sin could now become desirous. Man was given to struggle to achieve greatness.
Even a small deed of the person can take a big toll, or render monumental change for the better. Only man has the power to connect G-d with physicality. Only he is the gateway through which the universe becomes transformed. Little man has G-dly powers. One little smile, nice word or deed - can make or break. His behavior, and only his behavior, mediates between supernal G-d and our nether universe. We are G-d's fulcrum.
With so much power at our behest, we'd only be foolish to squander it. Let's resolve, therefore, to jump quantum leaps. Let's dare ourselves with lofty goals. Every day is an auspicious day. So, my friend, to quote G-d, "Where are you?"