a troll is actually a magical creature that wanders the internet doing stuff for the lulz, Grakelin probably thinks you don't actually believe the things you are defending, and just do it to make fun of us, because he thinks your arguments are ridiculous. i don't think their ridiculous, just misinformed and insulting, you're no troll, just a victim of a country too patriotic for it's own good.
There is already an international exchange of knowledge, actually it's been happening probably since the first cro-magnon met the first neanderthal, and happened through the ancient and modern times.
My sister is in med school studying under a Cuban teacher on an teacher exchange program, and a few of my teachers (i study fine arts) are on a collaborative project with a brazilian university and a few african villages, not just teaching, but learning from the local cultures. i'm not the kind of person that is into charity so i care little for the stuff they do in africa, but the african folk influence on some of my teachers' works is fascinating.
The american culture could also improve if they increased their importation of international books and films, and the rest of the world could also benefit culturally if the usa actually decreased it's exports of shitty books and crappy hollywood movies.
There are many decent american products, among which is dwarf fortress, and many crappy products from various places, but every year there's a new twilight, or da vinci code, and it's getting really tiresome to have to search among the piles of crap to find anything interesting.