I suppose your post is a good example of this - rather than an anonymous thumbs down, you were able to communicate in a more effective way - so perhaps you have a point! Having thought about it I can see the negative effect it might have, even if not anonymous. In fact I now think the dissent element is secondary to what I think might be the main enhancement which is a quick way to note that you liked the post.
For example, perhaps there could be only a "X users liked this post" and that is either anonymous or better, you can see who (registered users only) quickly marked your post as a useful one. I thought about this because in my personal schedule I have found the ability to catch quick snippets of various posts (iPhone in the cab; a quick look at lunch; perhaps a few minutes during the evenings) but not the time generally to write thoughtful posts (well sometimes, but perhaps not often enough!). This would be a nice way to quickly say "Thanks". In any case, the site is great already; this is nuance. All the best.