Despite my earlier comment, the way Sentry approaches open source is at least a little better than the majority, so its good that you at least provide an escape hatch that means heavy integration with Sentry isn't a complete vendor lock.

On your second point, you're right that self-hosting is cost cutting, but I found that when a business is growing, the features that sentry offers are more of a nice to have along the way, not quite critical to its success (No point capturing errors if no-one's using your bloody thing). Its easy to rack up that monthly bill with nothing but nice to have hosted services.

What I'd love to have is dumb versions of tools to self host initially when the requirements (and traffic) is very low. Kibana for example is a pig to self host, at one point it was taking up 25% of our production capacity. I found Loki is much better for simple cases in the beginning.

Good example that strikes a balance is Grafana / Prometheus. Its practically impossible to run a software shop without them, and everywhere I worked went through the same phases: Chuck a set of random containers in prod -> Deploy helm chart -> Migrate to Thanos -> Move to hosted Grafana when user/teams management gets out of hand.

Benefit is that absolutely everyone is familiar (and even likes) your tooling, I hope that's enough of a reason to give away a simpler offering.