This design change was made intentionally as part of the multi-level event changes.
In those changes, we removed the "quick comparison" event report in favor of more comprehensive event comparison reports. This was one thing that the copy event form was being used for.
Primarily, we removed the action to keep it contextually clear what the user was doing. The use cases we accounted for are as follows:
1) The user wants to copy a new event as a single level event. The user goes to the add event form, chooses the event information to copy, and fills out the necessary fields for the new event, and presses save.
2) The user wants to copy a new event into a hierarchy. The user goes to the hierarchy and selects the right position within it, clicks "add event", and follows the steps above.