I think the basic opportunity that Grudem has missed is to use the concrete-ness of creation in Genesis 1-3 to rebut the idealism that underpins much contemporary theology. A concrete creation consists of events that have a real-world time-space continuity with the events that we experience. The creation events are delimited in existential terms that are consistent with the terms by which we delimit events and causality in our everyday lives.
One of the chief de-limiters, of course, is timing. The passage goes to great length to define the chronological parameters: parameters that govern our understanding of cause, effect, and event relationships in uniform space-time, providing for their use in interpreting history and thus our being, our perception of our existence and the shared context of our communal relations. These extend not only ‘laterally’ with each other today, but ‘historically’ with those before us and in prospect of those to come, and ‘vertically’; our community with God and its disruption in sin.
The importance of time is that creates the event relationship with God; puts us and God in the one existential domain. Dislocation of event relationships (such as in a mythopoeic view of the creation passage) leads to a loss of event salience in our sphere of existence historical dis-junction and existential distortion.
When something happens controls it some way what it means to me, my decision and belief process and my apprehension of the basic historic dependence in concrete terms.
If we disperse the timing and time of creation into symbolism, then the connection with the real world and its salience for us and our relationship to God evaporates. This reduces the existential event-density making room for, indeed inviting, a range of responses that are outside relationship with God: these range from materialism (and its evolutionary speculations), mysticism (and philosophical idealism) -- exemplified in the modern western ‘new age’ movement and the demonic: asserted in all man-made religions!