I'm not suggesting the PerlMonks XP system should change, I'm just philosophising...
I have reflected at some length on the negative voting aspect myself. Negative votes are just that... negative. They're unpleasant, usually anonymous, and of little use when they are not accompanied by supporting comments. Additionally, I have seen instances where downvotes are applied to opinions, where the downvoting party disagreed on a posting which was not right or wrong, just a different opinion.
Despite all this, when applied correctly, negative votes are wonderful... votes which are applied to the information in posts, and not to the posting's author, style, sense of humor, opinion, etc. They keep the XP system working like a well-oiled machine... the more experienced monks dish out more votes, and the less experienced monks (such as myself) are kept where they won't do too much damage.
For all my reflecting I cannot conjure a better means to track experience than to allow both positive and negative votes. I did, however, come up with a couple ideas... whether or not they're worthwhile I don't know:
Another possibility is to have a model where there isn't necessarily a limit to the number of TIMES one can vote, but to the combined weight of all votes. So for example, a user could have X number of XP to distribute in the positive or negative, but that user can give those votes away in clumps, such as +4 or -2. The maximum size of the clumps, as well as the total amount of XP to distribute, is limited by level... so an Initiate may have 5 votes which he/she can only give away one at a time, and a Saint could have 30 votes which could be dispensed up to 8 at a time. While this idea introduces the ability for one user to make a much bigger difference upon another, which could be dangerous, the system itself should prevent any unpleasant, embittered people from attaining a high status, therefore the votes would usually be justified.
But, like I said, I don't think the existing system should change, I'm just philosophising.