Nearly no player enjoys the grind of memorising opening theory. But every high level player has to do months of it because every other player does months of it. It is a negative-sum equilibrium for them. Prep can be neutralised with prep but no chess player got into the game because they enjoy it.

So any variation that eliminates the need for preparation is a gain for both the winner and the loser.

And Magnus Carlsen is not a sore loser, he can both out-prep and out-calculate anyone in the world; hence the credibility of him suggesting that classical is not fun is higher than anyone else’s - because they could be called sore losers…