Many times you want to develop an action that should commit only when you know a transaction is final and only at this point should be commited.
But... sometimes you put inside a action a call to other action and if you dont have carefull to verify if this action as a commit inside (and this can have to be a recursive carefull...) you can start introducing a commit where you dont want in your initial action, and that can be a problem.
A action that contains a commit could turn red when inserted inside other action, so that the developer had the visual impact of the "blind" commit on his action.