What reason beyond wanting to be President does somebody need to run for President?
None, but it would be helpful to articulate how you are going to change things if you become President.
In the preliminary stages before she has even formed an exploratory committee? That's an absurd demand. A policy platform to deliver to the voters is something that is months away, not now.
He didn't say a policy platform
And it isn't like she was able to articulate a reason beyond her own ambition in 2008. She had a whole primary season to do that and failed miserably.