That's exactly why Magnus is now championing Free Style Chess, originally promoted by Fischer: you randomize the starting position of the pieces, which makes traditional opening theory useless. That cuts away a lot of the memorization and introduces a lot of new creativity.
It's not entirely surprising that both of these world champions saw that as a way to keep the game interesting.
Something else that Magnus sometimes does, even against fellow grandmasters, is play a completely ridiculous opening that's obviously bad. But more importantly, it's different, and all the existing opening theory goes out the window.
Including his recent "Berlin regret" against Caruana (which was more about bringing a position back into boring territory than trying for chaos, admittedly).
It's not entirely surprising that both of these world champions saw that as a way to keep the game interesting.
Something else that Magnus sometimes does, even against fellow grandmasters, is play a completely ridiculous opening that's obviously bad. But more importantly, it's different, and all the existing opening theory goes out the window.