Shelley's "Ozymandias" is given to us through the perspective of a traveler because he wanted to provide us with an accurate, objective account of the once-great pharaoh's decline.

A traveler in a strange land has no skin in the game, no reason to give a biased account of the sad remnants of Ozymandias's statue crumbling away in the middle of the desert. The traveler tells us what he saw and no more. This allows us to draw our own conclusions about the nature of earthly kingship.

Though a politically committed writer, Shelley wisely refrains from hitting us over the head with his strident republicanism and passionate abhorrence of tyranny. Instead, he presents us with a detailed account of what the traveler saw in the desert and allows us to make up our own minds.

Of course, Shelley wants his readers to come to the same conclusions as himself. He certainly doesn't want them to read the traveler's account and think that kingship is actually a great thing. But the way that the story is presented, even if it is factually based, gently nudges us towards a certain conclusion, a conclusion that corresponds closely to that of Shelley.