Because you know what you're arguing against or for better. Better understanding of the concept.
Connotation refers to a feeling used in a word in addition to its actual meaning.
Understanding connotation during an argument might help the speaker discern whether their counterpart is being negative or positive in their words, to which the speaker can respond by changing their tone. This will make others aware of the speaker's position towards other opinions, and will also make them value the argument even more.
