From Parts Unknown

'Would be lovely without, but having the observer on the right brings something to it.

I agree with HiHo, it really adds scale.....

The scale helps, but there's a visceral response in addition - seeing the observer experiencing the grandeur. Here, we can't see the observer's expression, but imagination often fills in the blanks. Imagine an image that includes the look on the face of someone seeing the Grand Canyon or Niagra falls for the first time. Or the thoughtful look or posture of one going to a particular place *because* its familiar or helps them sort out thoughts. This would be lovely with or without observer - but there's a different feel to each.