Glad to see it! Inklewriter in its past incarnation was a simple, visual, “play as you write” interface with Inkle’s special brand of magic for small or moderate-length choice narratives. In my experience, it bogged down a bit for larger stories, but check it out:
I think by high-value, they mean a password which you also use for other services and websites, especially for “important” ones like e-mail, Amazon, Paypal etc.; because if inklewriter’s security was breached and your password became known, then all those other accounts could be compromised as well. (Although, with a properly hashed and salted password storing scheme, that risk could be mitigated.)