Intuitive, form-conscious interfaces are definitely needed, but I think the hardware problem is the biggest hurdle facing wearables. Especially the battery design. I own a Pebble, and there is something significantly different about how I look at charging it... and that's with them doing everything they can to eek out battery life. This necessitates e-ink, accelerometer-based backlighting, etc. Having a beautiful display usually means abysmal battery life and an need to shake/touch your wearable every time you want to interact with it.