What's nice about "Hello, World!" is that it's a canonical example where we know exactly what it's supposed to do, in contrast these pages are showing off features of writing Spin components in different languages so that makes it much harder to compare.

In each case they're using a popular existing HTTP library for its familiar APIs, but the chosen APIs are of course not the same in Go and Rust.

The Go API (from net/http) follows typical Go style, it assumes success, and doesn't worry too much about errors. If you write any data to the ResponseWriter (which this example does), you get a 200 OK response anyway. You don't need to set types, it'll guess, likewise you don't need to care about binary data, it'll guess. This is cheerful and will mostly work, if it doesn't work you can probably learn what you did wrong and try again.

The Rust API (from the http crate) follows more typical Rust style. You must say whether you succeeded with Ok, so that failures can be handled appropriately. You can choose whether your response has a body we do have a body here so hence we need to write Some. Finally HTTP bodies are binary data, and we'd like to return a string, so we use the Into trait to get the UTF-8 encoded text out of the string as bytes, this is how Rust stores strings anyway so it will be trivial.

The Rust code sets header "foo" to "bar" for some reason, and also prints (to console) all the information about the request, presumably because that's trivial to do in Rust, the Go code doesn't do either of these things.

I agree that there certainly is a lot more Rust, it's just that I'd say it's beautiful rather than ugly, a matter of opinion.