I slightly disagree with how you think you have written. The problem is that HN and YC are highly technical. Most of us already know that web based CAD/numerical analysis is invaluable... What everyone is trying to figure out is YOUR approach. And there was not enough detail in it. You are constantly focusing on the bigger picture - which everybody has already granted.

You're in what I like to call "the nuclear fusion problem" - how the hell do you think you can pull it off ?

If I were you, I would talk about the innovation in the JS based symbolic solver (and that's pretty much what I would focus on from an implementation POV) and how you will use THAT to disrupt several industries.