Why create an engine?

There's been some discussion about why OPifex Entertainment is creating a brand new engine from scratch. There are already so many engines out there with the capabilities that we would need.
Unity
UDK
Moai
Ogre
And so many more
So what could we gain from creating an engine from scratch? The experience, the knowledge, an in depth understanding of how everything works and an increase in game performance.
First of all, we know we could create a game faster in another engine, no question about it. However, our team consists of engine programming junkies. We're in it for the experience. The desire to learn how it works, and to create something amazing.
The argument against creating an engine vs using an existing engine is nearly as old as video games are themeselves. We are re-creating the wheel to a degree, however, we are putting a modern take on the functionality of the engine and putting our own fingerprint on it. If you never try to improve on what's out there, it'll never get better. While Unity, or the likes, are amazing game creating machines, they're not for us. We're in it for the long haul, and we're willing to put in the time to create a product that will shine.
So with our choice to create a new engine, and with a focus on Ouya, we're primed to take full advantage of its capabilites, and quickly integrate with the SDK come December.