Agreed. It's usually best to find somebody with an offsetting skill set. While getting another tech founder will certainly increase your ability to produce quality technology it does not always lead to being able to properly identify a great idea with great potential.
I think that having complementary skill sets is important, but I'd say that after technical skills, interaction design skills are probably more important than business skills. Like they say: first get to product market fit, then grow the business. Getting to product market fit requires someone who understands user needs and interactions (product design) and someone who can implement the solution (technical). A product/interaction designer, though, will probably have some frontend development skills, so perhaps I'm arguing for two technical people.
I think for a business guy to NOT know design is un-excusable. Meaning how the user interacts with the app. He/she doesn't need to be able to code but to be able to mock up the UI for sure.
I agree, but one techie may not have all the tech skills he/she needs. Front-end expert needs back-end expert (and vice versa). Being an expert in both worlds is not as common. That's true for practically everything in life. But sure, given that you have your tech requirement satisfied, you'll be more well-rounded with a business guy too.
Right. But at least with one general knowledge techie and one general knowledge biz guy you can get a good read on tech issues/requirements and market opportunity. Thus once you get to this point you know what you need more of and more importantly you know what you don't know.
The best teams have well rounded/varying skills. Look at Ideo.com (company that invents stuff) - they look for well rounded individuals with passion. So while a team with more techies will produce better tech - not necessarily something that will be successful, a team that's more rounded has a higher chance to produce something that will succeed with inferior technology. That being said, web companies do not fail these days due to a lack of tech. So I implore those who know tech to look for people with differing skill sets and vice versa.