Why intentionally take out the one thing that makes your game worth playing?

Has anyone ever found out why they nerf something that in return makes the game worse?

Is the goal of playing a game not to have fun? When you take the fun out of the game then what is the point for the game to exist?

Even if they want to maximize their profits wouldnt it be in their best interest to make the game as great as it could possibly be?

​

Im sorry if I am beating a dead horse here but I just cant wrap my head around some of these changes. Why would you make something intentionally less fun?