Yes, I sent mine to overnight camp, but he wanted to go. He did not go with any friends, but it was a camp well known to our synagogue and supported/endorsed by the rabbis and the youth leaders. So there was a certain level of comfort. It was a fabulous experience and her went for 5 summers (half summers - 4 weeks because we also took a family vacation and he hung out with kids around here too).
No, I would never force him against his will.
I think there are many, many ways to expand a child's world and awareness. I think there is great benefit to having them "stretch" beyond what's comfortable and meet new kids. I think some kids can go away alone, some can go away with current friends (although this has pitfalls), and some can't go at all.
Camp has tons of benefits - independence, self-sufficiency, eating the food that's put out vs. kvetching about it all the time, cooperative efforts in cleaning/organizing the bunk, trying new sports and activities without having to sign up for an 8 week session like at home, and meeting kids from other parts of the country or world. But there are ways to give kids at home a lot of those experiences.
Encouraging a kid who is a little nervous is one thing - and a good open house and orientation program is really important. But pushing a kid who is just not ready developmentally or just not suited in personality to 4 or 8 weeks away, no way.