Voldemort is playing a very clever game. Declaring himself might have provoked open rebellion. Remaining masked has created confusion, uncertainty, and fear.
J. K. RowlingAnd his knowledge remained woefully incomplete, Harry! That which Voldemort does not value, he takes no trouble to comprehend. Of house-elves and children's tales, of love, loyalty, and innocence, Voldemort knows and understands nothing. Nothing. That they all have a power beyond his own, a power beyond the reach of any magic, is a truth he has never grasped.
J. K. RowlingSo then I thought, I'd like you to have something to remember me by, you know, if you ever meet some veela when you're off doing whatever you're doing.' I think dating opportunities are going to be pretty thin on the ground, to be honest.' There's a silver lining I've been looking for,' she whispered, and then she was kissing him as she never kissed him before, and Harry was kissing her back, and it was a blissful oblivion, better than firewhiskey; she was the only real thing in the world, Ginny, the feel of her, one hand on her back, the other in her long sweet-smelling hair.
J. K. RowlingDon't, Ginny, we'll send you loads of owls. We'll send you a Hogwarts toilet seat. George! Only joking, Mum.
J. K. Rowling