Hi, native AmE speaker here.
I'm not sure what you mean when you say that there aren't a lot of native english speakers on the internet. You may just not be looking in the right places. I understand that there may not be many native speakers who are willing to start up a correspondence with a person from a foreign country when it's difficult to make such a big commitment. I have, in the past, tried to find native speakers of arabic, spanish, italian, polish, and french in order to improve my foreign language skills, but many of them never really returned my emails/messages on this webpage. I had a correspondence with a hispanic person for a month, but then one of us may have gotten bored or whatever, and we stopped communicating.
Another big reason is security-the American media has continually showed the dangers of internet correspondence, which may be the reason why that one person was offended when you asked for their msn address. it's a scary age, and you never know who you can trust.
Don't give up.
- For Teachers