I realize that other text editors do this, but I've always found it to be annoying and never useful.

I've always appreciated your feedback bro, but just try to create a big table. I find an editor to be annoying if it doesn't allow me to add several rows/columns at the same time. Maybe there's {{research needed}}?

FWIW, this is the default behavior both in Excel and in Google Sheets (the latter also helpfully changes the right-click menu items to "Insert N above" / "Insert N below" when N rows are selected).

..or we could show two options when more than one cell is selected (Insert 1 above + Insert N above)

In T75227#1954434, @Esanders wrote:

..or we could show two options when more than one cell is selected (Insert 1 above + Insert N above)

That makes sense. That menu currently has 5 items, making that 7 in some circumstances wont clutter it and keep both options.