Having established choreography allows the dancers to be in unison, which enhances the overall performance of the dance. By establishing the steps and combinations in coordination with the music, all the dancers have a clear idea of what they should be doing and when. This allows the dance to be synchronized, which can be impressive to audience members.
Choreography allows the dance to be organized. When you have more than one dancer on the stage without established choreography, you run the risk of the dancers getting in each other's way, potentially resulting in an injury. Having choreography enables you to establish formations in the dance, where each dancer has a place she needs to be in during the various sections of the performance. This helps keep the dancing smooth and uninterrupted by chaos onstage.
Knowing the music and the steps enables you to make the most of the music. By scripting the dance, you can accent certain points in the song and varying beats in the music, showcasing the musicality of the dancers. When a dance is freestyle, you may miss an opportunity to accent a big move with a dramatic point in the music. Choreography ensures the music will work with you and not against you during the performance.
Creating choreography for a performance allows you to showcase the best of your dancers and hide the worst. If you have dancers who are particularly talented with a certain move, such as a switch leap or pirouettes, then you can incorporate this into the dance for those dancers while the rest of the group performs different choreography. By highlighting the best features and skills of your dancers by utilizing choreography, the dance becomes that much more impressive to the audience.