Another point is that 10mb is a lot of text, especially for users like me who use these types of note-taking apps as todo lists. For persistent notes I already have directory I store locally w/ cloud backup, but a webapp would be nice for my running todo list.

That will hopefully never top 10mb,so a free user like me would really eat into hosting costs. Perhaps a solution to people like the OP who are concerned about data being held hostage is to make it clear that after the trial period their data can be exported, that way they don't have to feel there is risk of it being held hostage.