It seems simple enough (though I know nothing about 3D character creation). My character can jump, but my companion has to path his or herself around obstacles - as small as a log - and sometimes gets stuck.

NPCs are capable of jumping. I've seen it. Companions just don't for some reason.

I've seriously never thought about that. Good question. You'd think it wouldn't be hard to program jumping into AI navigation behavior. Although, I'm SURE there's a reason they havent. Still, good question.