I don't think design alone, or technical skills alone are enough to get it done. Both are commodities. Anyone can throw up a spiffy iPhone app or web app with Node.JS in the backend. Not everyone, on the other hand has domain expertise, and can create a product with market fit, and sell it.

If you rely too much on your design skills, you'll end up creating something like Gowalla - something noone wants. if you rely too much on technological sexiness, you'll end up like SimpleGeo.. I bet they got 100,000+ lines of code altogether all for naught.