> wordpress is valuable because it allows very bad developers / marketing people to write very bad code and get away with it, driving extremely low cost solutions for clients who are cost concious.

You've sort of nailed it, but this isn't a bad thing. An alternative for these customers does not exist.

There's another vertical which is organizations that have armies of writers churning out content. Any kind of publisher or advertiser, basically. There is no better CMS for this. Large organizations like NYT, etc chose to write their own.