A variety of reasons.
I’d like to forget all the preconceived ideas, judgements & anger I have about him, and see what he is actually like..
Away from the media, away from the scrutinising eye of everyone in the world.
What is he like around his family?
What does he find interesting/funny?
What is his intelligence level REALLY like?

Plus, he is the President of the USA.. not many people can say they’ve met him!