Why is a blank line inserted after headlines and list items?
In org-mode, typing M-RET at the end of a headline will create a new headline of the same level on a new line. The same is true for plain lists. By default org-mode uses context to determine if a blank line should be inserted after each headline or plain list item when M-RET is pressed. For instance, if a there is a blank line before a headline, then typing M-RET at the end of the line will insert a blank line before the new headline.
