Isn't that what Ghost is aiming for? It's beautiful, has a great writing experience, is Open Source just like Wordpress, cheap hosting, and is working on expanding it's plugin ecosystem.
A lot of alternatives do individual X, Y, or Z functions better than WP. None I've seen have achieved a reasonable fraction (say, >40-70%) of the extremely broad set of aggregate requirements the entire developer, designer, and user communities would need to commit to a WP replacement.
Unfortunately, the can of worms that opens up in Wordpress is one of the worst things about it. Every plugin and theme is essentially its own ad-hoc web application running with global privileges.