That's a pretty fair criticism, and I have to agree with everything that you write here. But I don't see any way around that. I can't imagine a general interest site could possibly function like HN.
Some trolls make you think. Some trolls only hope to destroy online communities, and they are usually very good at it. It can be very hard sometimes to differentiate between the two.
Also, it's entirely possible to make people think without trolling (and I know you weren't claiming this). For example, your response to my remark made me think without being trollish. I personally prefer to participate in communities that promote your type of provocative comment, and not in ones where trolls are given free reign. But that's just me.