Durability has to apply to data more than it applies to the software that handles it.

I can't agree with this more. I'd like to build consensus on this to the point where we can put this down in law, so that data that belongs in the public arena (voting, public accounting, public records) is in a permanent, open, and documented format.

that puts limits on inventing and using new things, doing more with less, and doing stuff that was impossible last year/last month/last week.

This is true. Innovation will occur that won't fit nicely into old paradigms. Continuing my RFC analogy, that needn't prevent us from adopting new paradigms that include backward compatibility with the old, as well as new features.