Answer: For most plants seed pod formation takes a lot of energy. So, if you remove the spent flowers before they begin to develop seeds, the plant will produce additional flowers. If it were my plant I'd cut away the seed pods. The Brugmansia may have been stressed at some point over the last year and is reacting by setting lots of seed. (When a plant's health is threatened it often sets an abundance of seed.) If the plant looks otherwise healthy, just consider the seeds an extra bonus (they do add interest to the plant).
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