cre-ker

Kafka limits are customizable. 10MB is quite small. Kafka easily handles 100MB messages. If you need some temporal storage that works like a log then there's nothing better than kafka in terms of speed and scalability. But it's more about relatively long term storage. If you need to persist data for very short amount of time, why don't you use in-memory store? Do you have strict requirements around data loss? Something like Redis much just do the trick for out. With Redis cluster it even scales.

Go is actually one of the best in terms of design. Not every language has to be so complex. Go is easy to use and that's the point. Concurrency in it is best in class in many regards and that's what allowed the language to pretty much became THE language for backend, infrastructure and other web related things.

Rust is in completely different spectrum and doesn't compete with Go. It's much more complex, harder to write and read. That's the cost of safety. For kernel or browser engine - that's the compromise people are willing to take. For other applications - better use something else.

No they can't. UaF is impossible in memory safe languages like Go. Concurrency doesn't matter here. Only thing you would get is logical errors resulting in crashes or weird behavior.