I would like the auto number field to always be calculated whether a new row is added directly or copied/moved from another sheet. With current functionality, if a row is copied/moved from another sheet, and that sheet has a Auto Number column, the value from the original sheet populates the new sheet. This would be in line with all other system generated columns (modified by, modified, etc.)
There are many use cases for this, but I often use it in helper sheets to determine if the row entered is the most recent entry for a specific item, or to move specific columns from one sheet to another using a helper sheet.
If it's not possible to update the auto number functionality, then at least provide access to the system row. Add that as a new system generated column type.