I think it's silly to comment why you vote in one way or another. It's even more silly to comment only your negative votes, but not your positive votes, why one, but not the other?
What really is the point of Perlmonks? I think it's education and community. I don't generally comment on an upvote when I have nothing to add as it's truly pointless to just say "I agree, you're definitely right there." Usually, not always, but usually, when I down vote, I have a reason that might lend to the education of others, or myself when my reason is given and refuted. That's not pointless. When I upvote and I have something to add, I'll typically comment, also.
I will down vote a silly "Is too, is not, is too" argument, or some childish clearly off-topic, offensive or dangerous material without comment. Especially in the case that all that needs to be said has already been said, such as in the case of malicious scripts that have already been clearly identified as such.
Why don't we just get rid of this entire XP thingy?
I think XP adds to the atmosphere here. I encourage everyone to behold the wonder that is the highest upvoted node of all time.
Generally, it's more interesting to surf through the Daily, Weekly and All-Time Best nodes than to surf randomly, especially when you are short of time.
If you don't like XP, don't vote. If you don't want to see XP, login anonymously. You can still sign your nodes with a signature indicating it's abigail. Besides the frequent debates about XP, what's the downside of having it?