You make some really good points. I agree on the problems with only focusing on technology. I kinda did it myself on this project. As a programmer and designer (more designer than programmer actually) I dug my head in the sand and hacked away whiteout testing the idea and market early and often.
I also learned that the B2C market is difficult, especially if you want to make money. B2C almost always require a critical mass of users, and that's expensive. Unless you're passionate enough to spend hours on Twitter/Facebook/Community sites to build that mass. Which I wasn't (in this domain).
Having a partner would probably made things easier. And I will try to find one for my next project. Which definitely will be in a domain that I'm more passionate and knowledgeable about.