When it comes to building PCs, the mini-ITX form factor is where we've seen most design innovations.
While a mini-ITX build takes a little more patience and experience to do well, the rewards are much higher. Having a small, clean build in an interestingly compact package makes you feel good. Mini-ITX rigs make it easier to take your platform to a LAN party or play PC games in the living room (if that's your thing).
Veteran gaming PC builders looking for a challenge might want to take a crack at seeing what they can cram into a mini-ITX case and keep everything running without throttling.
Big PC power really can come in small packages.