History!
So, cc.engine has a long history to it, but prior to this version cc.engine was a Zope 3 application. And prior to that, it was other things, possibly derived from a mystical ether of butterflies and puppies.
Maybe the most interesting and relevant of this is why cc.engine is structured the way it currently is. For some reason I suspect that if someone else is to look at this in the future, they may wonder, "Why is this not a Django application?", presumably because Django is still the cool hip thing to program in in the python world, contains a lot of reusable cool components that can only work together in a Django sense, because it is what most python programmers know, and because gosh darn it people like it (and justifyably so). Well, there are a couple of reasons for why cc.engine is the way it is.
Django provides a lot of nice things: a generic user system, sessions, provides a database layer, etc. However, what cc.engine does is fairly minimal: it serves licenses and their rdf files and has a license chooser. It doesn't have a database in the SQL sense, but it does have one in the RDF sense..
cc.engine was rewritten during the "sanity" overhaul. During this period, many pieces of CC infrastructure were being rewritten. The prior cc.engine was written in Zope 2, and we knew we wanted to move away from that. Deciding that Django provided a lot of things but very few that were relevant to our needs, the original option that was considered was repoze.bfg, a minimalist framework that makes use of some zope components. However, partway through implementing that it was discovered that even the bits that were provided by repoze.bfg were not really necessary and lead to a lot of code bloat just to try to get them from interfering with what we did need, and that the entire system could be constructed in a very minimal wsgi application. And so, understanding what components were used and useful and what components weren't, reducing the application to a very minimal wsgi app wasn't so hard, and the end results were much cleaner.
And that's why things are the way they are, in case someone in the future ever wants to know (or I forget!).