Author here. I think async is a great feature to have - but I can't help but wonder if you're right. It might just be case of timing, but it seemed like once async was in the works, work on the rest of the language ceased. For awhile there all energy was poured into bikeshedding over how async would work. And I don't know if anyone is super happy with the result. Pin is a mess. Async functions still return anonymous objects - which cause all sorts of problems. And there still aren't coroutines in the language, even though async functions are implemented internally using coroutines anyway.

If we could go back in time and have the rust project decide to never implement async, I wonder what rust would look like today. There's a good chance the language & compiler would be much nicer as a result.