Why is poetry more philosophic than history?

It isn't always. It depends on the poetry, and the history. Sometimes you'll have straightforward history with just dates and few opinion-based conclusions, and a very philosophically idea poem... and in those cases it has some to do with how philosophy is accepted in poetry, and frowned upon (in certain instances) in historical documentation.

On the other hand, some kinds of poetry are very factual, and not philosophic. They tell things that really happened, or a real feeling. And some history is written in a very biased way, or draws conclusions based on the historian's world view without considering other viewpoints or possibilities... so not sure that we can accurately conclude that poetry is always more philosophic. :)