There’s something to be said for “scratching your own itch” as well. Not only are you in the best position to know exactly what you need the application to do, but you become more invested in the product and its success. Malcolm Gladwell puts it much more eloquently than me;

When you write a book, you need to have more than an interesting story. You need to have a desire to tell the story. You need to be personally invested in some way. If you’re going to live with something for two years, three years, the rest of your life, you need to care about it.