The universe as it stands is perceived by us to be 3 dimensional. Why is it that the universe formed into 3D space and not 4D or 5D space for example?
Assuming you're asking for a "first principles" explanation, there currently is none. That the world around us has three spatial dimensions is an obvious experimental fact, a raw input to our theories, not a derived statement.
Neither general relativity nor quantum field theory, which are our currently most fundamental theories, nor speculative theroies like string theory make four dimensions/three spatial dimensions really special or unique - the first two can be thought of in any dimension, and string theory naturally lives in 10 or 26 dimensions and must be "trimmed down" to the four dimensions we live in, which is possible, but not somehow implied as necessary by the theory itself.