I've been following this project for a while. Initially, they were going to have satellites at ~700km with another, even higher frequency constellation at ~400km. I remember thinking they must be planning to keep pumping these things out, because at 400km your satellite's orbit will decay over time due to atmospheric drag. That prospect actually really excited me because at that altitude you can compete with traditional fiber at even medium distances.
While you don't need to send your signal to space first with fiber, fiber has a refractive index of around ~1.5, meaning it takes your signal about 1.5x longer to reach the destination than it would traveling through a vacuum, an advantage you get with space.
One application I haven't seen them talk about is a hybrid ISP with a local fiber network that beams up to a LEO satellite backbone. I seriously considered trying to start a small ISP a couple years ago, and spent a long time researching the various costs and technologies out there. A lot of the cost is getting hooked up to a national/international network. You could deploy fiber locally, but avoid the need to deploy long-distance infrastructure by using satellites for the long-distance stuff.
You might even be looking at lower latency for international packets. Over a long enough distance, that light traveling ~50% faster could overtake a theoretical signal going through fiber.