Hi, whilst I am very sorry to hear that this young woman has died, I feel it is the walkers responsibility not to take risks- she was tramping in torrential rain, and it sounds like the creek crossing should not have been attampted, particularly without a travel companion.
I am sure trampers who enjoy tramping alone would not like to see rules introduced whereby you must have a travel buddy with you, although for safety's sake I think you should always travel in three's- I know we used to when we did our seven day trips.