I suppose being able to try out the API on the software level is useful, yes. I'm not sure how one is supposed to figure out whether results are likely to be good enough for a given application if they're so unpredictably degraded. I do suspect my perception is being colored by the website text, as quoted above.
Not at all. It lets you try out the API, figure out if it works for you, and get back "best effort" results. That seems perfect for a free tier.