It’s amazing how many good products were created by people scratching their own itch. Not just Linux.
I’m currently reading Design is how it works. Every chapter has a story about how a company uses design to create successful products. I’m just half way, but so far every story is a story about somebody scratching his/her own itch. It seems to create really great products, you really need to understand the customer. And there is no better way to understand the customer than by being the customer.
For agile teams this means that users need to be part of the team to create the best possible product.