Isn't this the fault of a bad UI mixed with bad defaults? I'm using the Cookieculler FF addon (https://addons.mozilla.org/en-US/firefox/addon/cookieculler/) to manage them. Instead of torturing me with a modal popup for every new site I visit, it keeps a list of hosts and cookies and trust status in the background. Using that list to protect important but delete/block all other cookies is quite convenient.