Agreed. That question could be added to the list. The problem though is that question rarely gets an honest answer from the startup founder. The founder HAS to say yes. It's best for the questioner to ask these other questions and then make a judgement on this one in the background.
Yeah, I don't know whether they would ask that. It's definitely something that entrepreneurs need to ask themselves though. I see too many people running around the Valley like chickens with their heads cut off, getting excited over solutions without a problem. Both technical guys who are so excited about the shiny product they're making and non-technical guys who are convinced that their "vision" is correct. As a technical guy, I don't write a single line of code until I have confirmed that there are actually people with a problem who will pay me for what I'm hawking.