This is a topic that we're continuing to iterate on between EBS, CloudWatch, and the AWS console team for metrics. When a newly introduced behavior makes step function changes in graphs displayed in the AWS console it doesn't meet the principle of least astonishment.

We're also continuing to investigate the reported latency in the console. Because this is a derived metric from VolumeTotal{Read,Write}Time and Volume{Read,Write}Ops, there may be a miscalculation happening due to the change in dimensions.