Sorry, we're working on allowing other login mechanisms. The publishing permission is so you can tweet out questions you ask easily if the box is checked. We never misuse any permissions.
While I realize that part of this comes from the structure that Twitter's authorization takes, which doesn't allow fine-grained permissions, ideally I'd love to see more sites asking which permissions you want to grant them. I almost never want to allow a site to tweet on my behalf (though I don't mind if it wants to send me over to Twitter with a suggested tweet), and I don't want to trust the site itself to not abuse the permission; I'd rather just not grant that permission in the first place.
We now prompt only for read access. Later on we might add back in some options to grant read+write access in order to more deeply integrate it with Twitter.