Is Astro very different from using another SSG like Hugo, then adding JavaScript in places you need it like type ahead search box or an interactive map? Given that it’s possible to add JavaScript to an SSG made site already, I don’t get what Astro does that’s different.
The biggest difference is that the DX is more like Next/Gatsby type frameworks, where you develop build/client with the same tooling and components, but unlike those frameworks most of your components don’t get bundled or run in the browser.
A great use case is if you like to work with an isomorphic component library, but you’re building a mostly-static site (in the sense that it’s mostly non-interactive). Tools like Next etc provide that DX, but they bundle/run that static content twice per page load. Astro only bundles the stuff you specifically mark as interactive.
This probably sounds trivial if you’re taking a more traditional approach to server/client responsibilities. But for anyone wanting to render on build and hydrate with the same component logic it’s a huge improvement over most of the current isomorphic approaches.