Most game developers want their players to finish their games so that they can see everything they worked so hard on to make. But some games force the players to complete all of the side content in the game to see the actual ending of the game. This can lead the player to get frustrated and bored by having to complete side missions just to see the finale of the game.
Batman: Arkham Knight Edit
To see the final ending and closure to the entire Batman Arkham trilogy, the game forces the player to complete a certain amount of side missions. These side missions are extremely boring and repetitive that it can get extremely frustrating and boring having to complete all of these side missions just to see the ending of the game you've spend your time playing. I never actually got to the ending of the game because I was so bored with the repetitive side missions that I felt like I was just wasting my time and so I just stopped playing the game altogether.