Ok, so you're suggesting that there is a correlation between how attractive a user interface is and the number of users/trolls?
Well then let's break it down to its most simplistic form, the Operating System, seeing as that affects every service.
How do you account for Windows and OSX, seeing as most of your trolls would come from Windows based machines and yet most people would agree that OSX has the superior/most attractive GUI?
I think you're over-generalizing. I'm only claiming that interface has a big effect on behavior you see in a particular place, not how the behavior got there. I certainly don't believe (and didn't mean to imply) that seeing an "attractive" interface causes a behavior change in an individual.
I also disagree that comparing operating systems is "simplistic". What operating system a person is using today is based on a huge number of factors, of which "attractive" is but one tiny piece -- a far more complex issue than what web chat you use.
What you're observing is what I'd call the same effect. People are lazy about sticking with an interface they know. AOL opening up USENET meant a bunch of jerks could screw things up, using the same interface they'd had. Digg/Reddit predate HN, and the jerks there aren't going to learn a new interface to be jerks to a smaller crowd here. Similarly, you're not going to change OS (and with it, interface) easily, so other effects dominate, and I'd expect most jerks, overall, to be using the most popular OS, overall. I don't know if that's true, but it fits my mental model.
Well then the effect you're describing has more to do with population density than interface?
When things start getting crowded, people start generally becoming rowdy - it seems to be human nature. You can have a small home party with 10-20 people and it's fine. Throw in a hundred gate crashers and it becomes a nightmare.
The thing with the internet is the anonymity that is afforded by such communities means that there is less of a barrier for people to become jerks. Look at YouTube or 4chan.
Youtube has a huge population and the comments are filled with volatile diatribe. Conversely, look at Vimeo - it's a much nicer interface, yet it doesn't have the same community issues that Youtube has.
Now let's look at 4chan. It has a simplistic user interface, but with extreme anonymity and a large enough population, it's the cesspool of the web.
I just don't think your "pretty interfaces = bad" argument has any merit.
Digg wasn't half bad when it FIRST came out, but as more people flocked to it, the quality went down. Ask a few of the old HNers and they'll argue the same about HN since it has grown in size, they argue that the quality has gone down. I mean, we see a thread complaining about it almost every other week it feels like.
Well then let's break it down to its most simplistic form, the Operating System, seeing as that affects every service.
How do you account for Windows and OSX, seeing as most of your trolls would come from Windows based machines and yet most people would agree that OSX has the superior/most attractive GUI?
Just curious.