Question: why was ozymandias written as a sonnet?
Answer: Still, “Ozymandias” is a masterful sonnet. ... Ozymandias is first and foremost a metaphor for the ephemeral nature of political power, and in that sense the poem is Shelley's most outstanding political sonnet, trading the specific rage of a poem like “England in 1819” for the crushing impersonal metaphor of the statue.