As you point out, the way to do that today is with time travel" in the map view, so you can put the datastore of interest "in context" and go back to the point in time to see what VMs were on that datastore.
There is no way to generally query historical data currently. Do you find the map view lacking for this use case?
The Map view is great for seeing the state of the environment at that time (it would be even better if the component names weren't truncated), but that view is not ideal for, e.g., presenting reports to management about conditions immediately preceding an outage. For example, if a host goes down and HA kicks in to move the VMs from that host to other hosts in the cluster, it would be useful to run a report showing which VMs were on the host at the time. That information can be extracted from the Map view (although it's cumbersome--see my other recent post), but being able to run arbitrary queries against a particular date range would be very useful. I guess you can consider that another enhancement request if the functionality is not already available.