I think because it's interesting to hear what people have experienced when moving existing thing to Rust.

How hard was the task? My personal experience has been that it's often hard

What performance benefits did you get? Insane drop in resource usage is what I've seen

What did you contribute to the young Rust ecosystem? Many people end up fixing existing weaknesses or problems to get existing thing rebuilt.

I think these and others, get many of us interested in these types of submissions.