What is the purpose of balancing a chemical equation?
To determine the stoichiometric relationship between species.
The truth is, there a lot of reasons on why to balance chemical reactions/equations. But in my opinion, the main reason is to determine the stoichiometric relationship between species.
Say for example,
Let the above reaction be balanced where A, B, C, and D are different chemical species.
From the reaction, it may be concluded that the production of 4 moles of C requires 3 moles of A. Also, the production of 4 moles of C requires 2 moles of B.