How does that follow?

If someone is willing to use it even when it's absurdly cumbersome then they are going to turn into customers. Once you build it you can iterate to find the best patterns.

Our experience was to the contrary. It's not shown in the blog post, but users were thanked for their feedback immediately.

The reaction was overwhelmingly positive; people were excited that we were building something in this space.

If a good one exists already that is. And if that is the case why are they checking broken demos? Why are they given their email addresses to broken demos? Either way you slice it, if something like this gains interest it certainly illustrates opportunities.

I think it's natural to think that people will react this way. It turns out that people react completely differently. In my experience employing this tactic across several different verticals (SaaS, ecommerce, games), I have found people to react positively (yes, please make this!!) or neutral/mildly disappointed (darn, I wanted to use that). Never resentful.