Well, I can't speak to your experience. It's unfortunate that some that homeschool don't do a good job of it. But studies show that home schooled students are as well adjusted, or better then their conventionaly schooled peers. So your experience just isn't typical. I guess the few you have met are just not up to par. Not everybody is cut out for homeschooling their kids.
As far as fear being a motivation, well yeah. A lot of things we do are motivated out of fear. That's not a bad thing all the time. Most people that homeschool though do it because the public schools just can't do it as well.
Here's a good document put out by the US department of Education. Doesn't speak to the issue of social aptitude of students, but shows the type of people that homeschool (basically people from every group in society) and their reasons for doing so.
http://nces.ed.gov/pubs2001/2001033.pdf