Until now the number of comments under the SEQ RERUN posts has been rather low. The most interesting sequence posts are obviously yet to come, but still it seems quite surprising, given how much people have endorsed the idea of reposting the Sequences. Plausible explanations are: that commenting a post under a different post feels unnatural, or that clicking the link to the old Sequence post is enough inconvenient that people don't actually re-read it. I suppose that the number of comments will be greater if the original article is pasted in the rerun post.