The goal of the call is to eliminate upstream pseudo-directory blobs. I fear removing it would do bad things.
But if it is called after every file is written, it will be expensive, especially as there is getStatus() in there (2 x getObjectMetadata() + 1 x listObjects()) , plus the deleteObjects() call. As this goes up the tree, the cost will be O(depth)
Given that after a file has just been written, it is known that there is a child of any directory (i.e. it is non-empty), then you don't need to check so much. You look for the existence of a path, and if there: delete.
More deviously, you could say "delete the path without checking to see if it exists". If it's not there, a failed delete is harmless. That'd still be O(depth), but one S3 call, rather than 3 or 4.
And, once you go down that path, you could say "queue up a delete for all parent paths and fire them off in one go", going from O(depth) to O(1).
Even better, you could maybe even do that asynchronously. I'd worry a bit there about race conditions between the current thread and process, but given this is just a cleanup, it might be safe —and I don't see it being any worse race-wise than what exists today, except now it may be more visible to a single thread.
That would need very, very, careful testing. The one thing nobody wants is an over-zealous delete operation to lose data.