Well I think it happened because a large number of Rust committers, core-devs doubled down on multi-year Rust async effort. What larger ecosystem would take away from this?

IMO the message was Async is the future so everyone better hop on this train.

I didn't get that message at all. The length of time it took to add async sugar made sense given what they were trying to do. It was not a statement regarding the suitability of it for every use case not should it have been.

the problem with async is it makes easy things much more complex if you don't need the performance. granted it should be easy for library/API designers to provide sync versions of all async calls, but I don't know if this happens.