always loved Lessa!)
What makes her even more powerful as a character is that she arranged the murder of her first victim when she was an eleven year old girl...

As for the psychic powers - I suppose a lot of her later books were more explicitly about those (like the Pegasus and Rowan books) so she chose to makle Pern different. Although if the books are all supposed to be set in the same universe, presumably the settlers of Pern simply forgot/lost their more detailed knowledge of psionics over time.