Is this one of those troll comments to which we should respond by saying something nice? Because if it were an American making a similar comment in reverse, then it would be buried as jingoistic/xenaphobic/racist/etc.
You look great today.
Both of these things put me on edge with americans who, on average, despise passive aggressiveness and use sarcasm as if it were the salt of conversation. The result is that i have to think in a completely different mindset to talk to US people, to avoid misunderstanding them or having them be disgusted by the way i talk.
On a more serious note, I too have noticed a shift in the comments on this site; I really enjoyed the fact that HN was a more "serious" place for sober discussion, where most comments were useful (larger signal-to-noise ratio). This culture made me reconcider my own comments on a few occasions.
EDIT: Not saying that this is a huge problem - just a development I don't enjoy.
Being a marketing platform, I would imagine something like the maximum number of people within their target audience engaging.
And two: not having facts/discussions which tarnish their company's image on the platform.