Traditional advertising techniques scubas the use of celebrities has been replaced by whimsical characters and animations. I think this has happened as it accommodates to a much wider audience, if you look at the Bear and the Hare John Lewis Advert this is a great example of this. The storybook-esque tale appeals to both auger and older audiences.
The colours and cartoon characters appeal to children as they are more likely to enjoy the advert because of this. Also, the story is of two animals who wouldn't necessarily be 'friends' the real world and how they come together at Christmas time despite the unlikelihood of this actually happening. It shows a Bear who would usually hibernate through Christmas sleeping and his friend the hare is upset that they aren't spending time together. But after the Hare leaves him a present the Bear come out and spends time with all the there animals. The story of friendship appeals to the audience as it promotes the ideology of friendship.
However, this advert hasn't completely left the realm of traditional mediums as the use of Lilly Allen and her song which is soft and almost like a lullaby helps the advert become more memorable for older and younger audiences.