The introduction characterizes the first discipline through this aim:
الِاحْتِرَازُ عَنِ الْخَطَإِ فِي تَأْدِيَةِ الْمَعْنَى الْمُرَادِ
Avoiding error in communicating the intended meaning.
Grammatical correctness alone does not guarantee that the speaker's intended meaning is properly conveyed to a particular audience in a particular situation. Some contexts call for emphasis; others call for a simple statement or brevity.
Muqtada al-hal means the demand of the communicative situation, not a purely personal preference.