For Ctrl + + to automatically insert a row, you have to do the extra
step of highlighting the whole row first. If you don't, you'll get a
dialog box requiring you to make a choice and then either hit Enter or
click OK. To me, that's not really a shortcut.

The speed key sequence Alt+I,R to me is much quicker and simpler -
you don't have to highlight the row first and you don't have to deal
with a dialog box. (By the way, Alt+I,C will automatically insert a
column.)