Having four stereocenters, glucose is one of a set of sixteen stereoisomers - two to the fourth power.

Sugar and carbohydrate chemistry represents a system which evolved and established billions of years ago. Energy metabolism involves harvesting electrons from nutrient molecules and passing these to an oxidizing agent to power establishment of phosphoryl transfer potential. A structural change, like the addition of a second carbonyl group would be suboptimal in the sense that there would be fewer electrons under the control of carbon in the sugar to pass to the acceptor. Glucose represents a compromise between its power as a reducing agent and solubility. On the other hand, asking why glucose and not one of its stereoisomers is the central sugar for energy metabolism is a complicated, unanswerable question.

The sugars in biochemistry have ancient connections through pathways to alpha keto acids like pyruvate and oxaloacetate and to amino acids. They have ancient connections to each other through isomerase and epimerase. Symmetries were broken eons ago and the pathways established involving the stereospecific participants in metabolism. It is what it is because that's what it is.