The structure is consistent with other bundles. But the question is, are bundles really the logical way to handle documentation? I don't think so.

If you look in places like "/Library/Application Support", everything is basically broken down by product or vendor. It is hard to imagine having so much documentation installed that similar naming wouldn't suffice for DocSets.

Apple has also used saner documentation layouts elsewhere (and oddly, in places that are probably not meant to be "public" documentation). For instance, there's a /Library/Documentation, and its layout is very easy to follow.