I like the rep system, even if I get a few red cards. I can know what others thought of my posts, even if it's negative feedback. Anyways, I'll continue posting with the same opinion, despite continued negative feedback. I'm just that way, and have accrued a total of eight for a couple of posts, just cause the liberals weren't understanding my argument (they agreed with me later). This of course took place at another forum.
Others can honestly give their true opinion without fear of someone getting angry, or upset at them. Sure, it would be better if people could actually articulate their disagreements in posts, but some won't bother.
I also like to let other people know that theirs was a good post, and occasionally that theirs was bad. I usually never sign either good or bad reps though, just so that people remain objective when they read my posts, and disagree when they disagree (I've noticed on other boards that people stopped disagreeing when I had given them some signed positive rep). I put my opinion/beliefs down, and I hope people can actually challenge me to look at it differently.