I'm pretty sure I'm fairly far from your target customer, given that I'm not building products, and right now my only usage of fly.io is to host a tiny app that

I'm pretty sure I'm fairly far from your target customer, given that I'm not building products, and right now my only usage of fly.io is to host a tiny app that expects to be used a few times per year by my spouse and me. Having said that, the reason why I personally would be happier with the ability to set a hard cap is that if I'm going to put a project on fly.io, I'm spending my own personal money on it. If I'm spending my own personal money on it, I want a guarantee that it cannot possibly cost more than a given amount. When it's my own money on the line, I absolutely want the service to shut down rather than have even 0.01% chance of costing me a lot of money. The moment I'm actually building something for a business, the moment it's company money instead of personal money, then priorities change and everything you're saying makes sense. But as long as I'm just a single developer playing with stuff and billing it to my personal credit card, I want that guarantee that I won't accidentally make myself go broke.