Ratings are definitely the most requested feature for Link Library, but I also feel like it’s the type of feature that most users will have diverging opinions on, thus being a bit of a headache to implement.
From what I can see, some users want to see a rating-based system as you are proposing, while others would like to see a upvote / downvote type system, similar to reddit or stackexchange. While the first person in this thread was talking about a straight 1-5 star system, what you are talking sounds more like an upvote/downvote/rating hybrid to be able to assign a negative star rating to even further lower a link’s rating.
Some other topics that come to mind when it comes to ratings as well are whether only registered users should be allowed to rate, or all users. If all users, then does the plugin need to start tracking IP addressed of users to avoid repeat voters, but that could easily be tricked. Should users also be able to change their vote over time?
Once a decent number of users have chimed in, it will be easier to start working on this feature with confidence. Having a better definition of the feature would also help me get a better idea of the time involved, thus being able to indicate better a donation goal to reach to push this along.