Lots of folks have tried to force Wordpress to be more than a blog platform. I've always seen these efforts in the same light as when guys dumps tons of money and time squeezing horsepower of a Honda Civic: end of the day, it's still a Civic that get its lunch eaten by a stock 'Vette.
Look, you just don't get power and flexibility in the same package as intuitive and simple. The best you can do is cut one to boost another. Take iOS. Intuitive as hell. Flexible as a piece of rebar.
Drupal's been mentioned in other comments. It's crazy powerful and very flexible... it's the Corvette to the hopped up Civic that is Wordpress. It's also hard to learn, the interface can be...challenging and the plumbing is complex.
Edit: Downvote me if you must but at least communicate why...did you build a 11 second Civic or something? ;)
Exactly. It's still a fucking Honda, and for the time/money spent on it you should have bought a Lexus. Similarly you can tweak wordpress all day long, in the end it's a blogging software.
Wordpress is the PHP of web publishing platforms. The barrier to entry is low, you can get decent results quickly, and it provides a great deal of power to the unskilled user. There are lots of things that it's good for; I'd say, in fact that in most cases it's all a company needs.
But it's really easy for it to become the only tool in the box, and pretty soon someone is in over his head trying to brute force it into being the solution to a problem that it was never designed to solve.
Now on the other hand, if you started with a British Mini...
At the risk of being pedantic, I think you mean Acura (http://en.wikipedia.org/wiki/Acura).