These mostly seem like bad ideas:
#1 This is the only good feature listed. It helps people skim comment threads for a relevant discussion.
#2 Without this feature, people are encouraged to think before voting, and only vote when they mean it.
#3 Without this feature, people are encouraged to use HN as a transient source of news and intellectual discussion, and not twitter.
#4 Without this feature, people are encouraged to go away and do real stuff until enough time has passed that the front page is new again.
#5 Without this feature, people are encouraged to read or discuss an article based on its own merits, not just what appeals most to hivemind upvotes.