A useful distinction is between intrinsic excellence and incidental excellence. Intrinsic beauty belongs to the utterance insofar as its expression is fasih and suited to the occasion; it is part of the present account of balagha.
An attractive handwriting style, melodious recitation or a pleasant room can add incidental appeal. Such external features may help reception, but they cannot by themselves transform an ill-formed or unsuitable sentence into rhetorically excellent discourse.
To assess balagha, mentally set external packaging aside and evaluate wording, communicated meaning and contextual fit.