One of the downsides of serverless is that it can be difficult to predict the overall monthly cost when the granularity of billing (per invocation, memory usage, or execution time) is complex. For developers this might be totally fine (even preferred), but we think that giving a single, predictable price: Hydra $100 / month is better for businesses to plan around.
Usage caps per plan are purely soft limits so users don't actually encounter them. Yes, we want people to upgrade to higher plans. In the words of Maya Angelou "Be careful when a naked person offers you a shirt" - meaning, we believe these are the best prices we can offer today to build a sustainable project on. That said, I appreciate your point about our # of users limit. If we removed that limit would you try out Hydra?