One thing you didn’t mention is that there’s currently not a good way to find a node by it’s uriPathSegment property since it’s stored in a json array. This is the reason for the current implementation. There’s a change in review to improve that though https://github.com/neos/neos-development-collection/pull/1, which would make it possible.
However there is a potential performance issue with the other approach. If you have lots of document nodes in the database it can take quite some time to search through them to find those matching the path with a LIKE statement. In some cases it could be more performant to use the current implementation. Of course this can be solved with optimized with the proposed changes in Discussions - Neos Sprint 2015 - Frankfurt