It is what it is. I think for your purposes you should be able to use either method, but the trigger event action is obviously for triggering events, and requires two parameters, not one.
You can also include a payload in your event to make it more versatile. In this case the event could be "key press" and the payload could be the key. In the command that is triggered by the event, you can use {1} to get the value of the key.