If you're making games, you're making experiences. Each element of your game in some way contributes to the overall experience, whether it's graphics, story or a certain sound effect.
It subsequently comes as no surprise that in order to understand how to effectively craft an experience for the player, you need to understand how a specific element makes a player feel. Whether you realize it or not, game development is a game of empathy.
As the developer of your game, you are the worst critic of your game. Your perspective is the most likely to be warped from hundreds of hours spent thinking about or playing with it, as well as the knowledge of all the past iterations and even the original vision for the game. These all contribute to making your opinion of your game nearly useless. I'm not saying that you shouldn't play-test your game, because you definitely should. Some things are universally recognizable. The point I'm making is that there are innate biases in a developer's perspective.
Simply put, you need new perspectives.
You need players to tell you what is wrong with your game as well as what is right. You need players to tell you what the game makes them feel. You need players to tell you what other games make them feel. You need to read what other developers are saying. You need to listen to stories from other developers.
Without all of this, it's going to make developing a game very hard. The worst thing you can do is fail to empathize with the people who will be playing your game.
Of course, it's not just the players. You need to be able to empathize with the stories of other developers, especially if you're just starting out. Without being able to get a comprehensive view of the industry and how it treats people, you're in for a rough ride. The next time you're listening to a talk at GDC and the developer spends the first 15 minutes introducing themselves, stick with it and listen to them. Chances are that by watching this, you're understanding the biases and path through the industry by which the developer came to be.
No two people live the exact same life. Even if they did, it would be exceedingly rare. Making a game for yourself is great and I don't mean to say I discourage it, but if you're expecting other people to listen you have to make a game for them too. This applies doubly if you're selling your game.
Next time you're drawing a sprite, writing a plot twist or composing a soundtrack, try to find someone who you can ask about it. Ideally, don't have this be friends or family, though if you're in dire need of a new perspective they'll do. Do this as often as possible for as many iterations of your game as you can. It will help.
I hope you found this informative or otherwise enjoyable. Thanks for reading!
...and good luck with Ludum Dare 38!