Add 'duplicate' or 'repeat' to right-click menu
To insert a copy of selected rows or columns requires: select - copy (ctrl-c) - right click - insert copied cells.
How about: select - right click - insert selection above
Kenneth Barber commented
What about cutting? What about individual cells as opposed to entire rows or columns? Is Ctrl + C really that bad?
You are also missing one big advantage to the current method. After you copy your range, you can select a new range and then paste the copied cells. This gives you duplicates across multiple rows or columns.