What about penalizing folks with excessive negative feedback by not allowing them to neg others? You could either use a "straight" number -- say 25 or 30 negs. OR you could build in a "qualifier". Require anyone with over 20 negs to earn at least 60 positives, say, before they can use the feedback system again.
Some few folks seem to be using neg for straight retaliation for losses or their own negs (even well-deserved). Though folks who play a lot of games can rack up a fair number of negs with no real justification, when people start getting 20 and 30 ... something is going on. Though I don't expect you to be our "Nanny", neither should these few jerks be allowed to ruin the "reputation" of everyone they play just because they think it is funny or because they have a bad attitude themselves. I realize that some folks even consider this bashing "part of the game". That's fine as long as everyone is on the same page. However, why should someone like (well, skip the name, but let's just say someone with over 20 negs to only 40 pos right now) be able to neg someone with 70 positive and NO negs just because they lost? OR to neg someone who is just starting out. Also, at some point allowing these idiots to keep negging just defeats legitimate negs.
Currently, the only way to avoid these folks is to only enter games as the last person or only play private games -- pretty limiting options. To put someone on the ignore list, you have to know who they are in advance. Generally, that means you have already played a game with them .. by which time, it is sometimes too late to avoid a neg. You could argue that unwarranted negs don't really matter because anyone reading them and seeing the rater can tell who is reasonable and who isn't, but that takes a lot of extra time. Also, if negs are not going to matter, then why even have them? You have them because they DO matter -- at least to those who use it legitimately
It is tempting to ask for a game option "let's be nice" or "no swearing" . However, the reality is that some folks would just use that as an excuse to go in and be as obnoxious as possible. (say, maybe an "obnoxious game" option might work ????). The ignore button helps, but you have to know someone exists to use it. The big remaining, solveable problem is abuse of feedback. This would be a way to help solve that without requiring you to go in and interfere in any but the MOST serious cases (actual threats of violence, for example)
This would be a way to deal with those folks who just plain have no use for the feedback system and choose to ruin for others, for those who's behavior might not be quite bad enough to actually kick out, or it could be used to reinforce a warning you give to folks in danger of being kicked out.
This won't keep out all unwarranted negs. Folks who play lots of games will probably still get them and they will, in turn, more or less balance out with the many positives they will also likely receive. For that matter, even someone with 70 positives can have a bad day and maybe DESERVE a neg. However, there are enough "jerks" out there to ruin the system/"reputation" of the rest. This will keep those few people from ruining the whole system while still allowing those who like the aggressiveness and back-biting to pursue their own games.