Personally, I migrated to homebrew due to the ease of writing packages compared to macports. But I happen to enjoy ruby more than custom DSLs. It's probably a division similar to Chef/Puppet.
Having switched and then switched back, I will agree with you. If you're inclined to write your own package installers, Homebrew is worlds better than MacPorts. But otherwise, MacPorts has many more packages that-just-work.