I think there is a place for a bit of whit every now and again, what we want to avoid is having threads devolve into long lists of one-sentence banter. If you study the structure of these sorts of threads on reddit, I think one of the best tweaks we could make to avoid that sort of rot would be to auto-collapse any reply thread that has x% of replies that are under a certain character count unless the parent comment has a relatively high karma value. As you pointed out, sometimes the pithy statement is needed to break the ice, but rarely would and valuable discussion involve 6-7 one-sentence replies in a row, which is what you get when a conversation on reddit devolves to a joke-fest.

Auto-collapsing threads for comments that are below a certain karma threshold seems like a nice tool as well - it still allows access if you want to parse the thread, and trolls still have a place to do trollish things, but it moves the behavior into an opt-in situation where you have to actually click on the thread in order to see it.