If you haven't worked in the game industry, you might think of a game designer job as a dream job. You get to create your own toys and then play with them! Well it certainly has its moments, but it's important to realize that the job is still a job. There will always be boring parts that need to be done. And more often than not, the job involves creating your own toys and then figuring out why the won't work or aren't fun. In fact, it's a lot like every other programming job except you get to make toys rather than spreadsheets, word processors, or websites. While it's fun to design toys for a living, there's a pretty high cost to it. And I don't mean the "there's boring stuff too" cost that comes with every job. Here is the cost:
The more time you spend designing a game, the harder it is to enjoy playing it.
The problem is that over time, you have to think of the game in terms of its individual core mechanics. But the wonder and enjoyment comes from how those mechanics are organized into something greater. No game has infinite replayability. There always comes a point where you think, "That was fun, but I won't ever want to play this game again." A game might have 10 hours of good fun, or even 100 or 1000. But no game is fun after 10,000 hours. Why is that? Why can't games be fun forever?
Games are mind candy.
They are a thought treat. Personally I approach games as puzzles to solve. The very act of thinking is fun, at least for my mind. The challenge is learning how the make the best move in each novel situation the game presents. As you play a game more, you learn it better. And eventually you simply recognize the situation and can play on autopilot. At that point the game ceases to be fun because it is no longer challenging. It can still be entertaining to execute the actions, and in playing I can encounter a few new challenges, but in general the candy of the game no longer tastes sweet to my mind.
Unfortunately, my job as a game designer isn't done until I've solved the game and determined there are no degenerate solutions. The harder it is to determine a game's optimal solution, the more replayability it has. (Note that replayability just defines how long it takes for the game to cease being fun. It has nothing to do with whether or not the game is fun in the first place, or to what extent.) If it's too easy to solve the game due to an obvious dominant strategy, no one will have fun playing the game once they figure it out and all my design work is for nothing.
While I'm not an author, composer, or movie producer, I suspect this problem extends to all jobs designing entertainment. A really satisfying book is one where all the plot pieces fit together nicely and there are no obvious plot holes. The characters need to feel genuine and you need to understand how their development as people natural extends from their personalities and experiences. No author can convincingly do that without really getting into the minds and lives of these fictional people. To build the depth of a good book, the author must understand that depth before the final editing pass is done and the book is sent to print. They will never have the enjoyment and wonder of watching how the lives of their characters unfold. They sacrifice that potential joy so that other people can experience it too. It's just part of the creative process.
For my part, I find I don't enjoy playing first person shooters as much as I did many years ago. Maybe after a few years break I'll enjoy them again, but that's just the personal price I paid so that other people get more enjoyment from the games they play.