This is such an important test that we have a question about it on the application form. I learned about this heuristic from Sequoia, who care a lot about it. They call it "proxy for demand."
Christensen talks about this too, as "non-consumers" who have a job they need to get done, but can't because they lack skills, or money. Instead, they pay a professional to do it for them, or "cobble together a solution". There are also "non-consuming contexts" where you just can't use a product (e.g. a landline phone in a car).
What I found really interesting was that the reason successful disruptions are "more convenient, simpler and/or cheaper" is not because that's an improvement, but because it enables the disruption to be used by non-consumers... (who lack the skills for a complex product; or the money for an expensive one; or access to an inconvenient one.) They are delighted to have a solution better than what they have now, so it doesn't need to be as good as the incumbents'. Secondly, if it's not good enough to appeal to incumbents' customers, it won't provoke a competitive response.
