Steve,
You're right that Rutherfords (slightly different) comment almost certainly came first; "If you can't explain your physics to a barmaid, it is probably not very good physics."
But I quoted Einstein's; "you should be able to explain physics to a barmaid," which I'm sure was derived from it, as much of his work (and most of all of ours!)
The point is I think both are very wise and true but don't you agree habitually ignored by most of the academic community?
On the Cosmos; I agree. As a Cosmologist ('observational') and RAS Fellow I feel the need to focus attention on understanding the cosmos better before we try to fly beyond it. That's not to say I don't explore hints from the data now & then!
I gave your essay a 1st speedread and hope you'll be pleased I market it as worth reading again & discussing. Being brief may have helped in that but I found that didn't diminish quality.
I wonder if you read & understood mine and have any intelligible questions or comments? (doing so in conjunction with Declan Trail's helps).
Very best
Peter