I'd rather have the choice to pick and the choice to switch later: some thousands of calls can be okay during initial development/testing and the first days of the product, then as I use the API more extensively, I switch to a subscription.

This is similar to how most online content is sold: most require you to subscribe. I follow some NYTimes newsletters, and I'd pay for the individual articles I read, but I don't want to subscribe, even if that may end up being cheaper sometimes.