I've been saying that too, 'reason for downvote' or 'link to profile page'
What if I told you that you can just click on the comment permlink, and that gets rid of the graying. Nobody's being "silenced" here; it's just a way to quickly assess the level of confidence in a HN comment.
Is it even a good measure though? Is the community more "confident" in a post that has 1 downvote than a post that has 50 upvotes and 52 downvotes?
HN (and many, MANY other sites, including forums, product reviews, search engines) confuses "popularity" with "quality". If there was one thing on the Internet I could fix by waving a magic wand, it would be this idea that more people [liking|linking|upvoting] something means it is better. Crowdsourced curation doesn't work.
What is worse, it is an entirely silent way of silencing dissent. I would love to experiment with the other end of the spectrum: not only should the number of downvotes be visible, downvoting someone should also require a reason to be given, in the form of a post. And it should be possible to downvote those reasons too, with the algorithm adjusting the original downvote's weight based on the score of the downvote reason.