I agree! I have heard of studios making their own version of actor spawning that somehow uses the incremental component registration of the level streaming code. It would be great to have something like that native in the engine. It wouldn’t be fully “async” though, as in running on another thread, but more like incremental spawning, as in running time sliced on the game thread like level streaming does now.
I don’t know if we’re currently working on anything like that (doesn’t mean we’re not), but the team is at least aware of the demand.