I can't say whether parents should homeschool their children or not, if it works for you that is wonderful. My parents decided to send me to private school, so I could learn in a more individualized environment while interacting with my peers, but that is not to say that homeschooling or public schools are bad. So please, if your lifestyle works for you, I'm glad, but don't think I'm out for a witch hunt. 
I am however, worried about the fact that some (by no means all, so I'm not generalizing by any means) homeschooling parents focus so hard on academics, that they forget that the child will eventually have to go out into the real world. While homeschoolers may have better scores on standardized tests, great, but a standardized test does not say much about real-world skill. Also, it's very nice to see parents putting their children in organized activities such as scouting, dance, etc. but what about the non-structured activities? Kids need socialization outside of those types of activities (both traditionally schooled children and homeschooled children). I understand parents wanting to keep their children away from peer pressure and the like, but in college this runs rampant--and also carries into adulthood. Some life skills cannot be taught from a book. Kids get into trouble sometimes--that's what they do while learning to be adults. Passing notes and detention and whatnot may seem undesirable, but that's why they're kids! Some social skills are not learned in a structurized group, but while just hanging with friends after school, during school etc. Cliques are formed in school, and they are a part of adult life as well. If a child has never been exposed to that, then when they get to college and enter the workforce, they may not know how to deal with that, and it could possibly have a negative effect on self esteem. Drugs are everywhere, so even if you manage to keep a child away from that now, when they grow up they will have to deal with that reality. 
Also, some homeschooled children are so advanced that they graduate years ahead of their contemporaries, and that should be applauded. However, graduating before your friends may not be so great. When I was in college, there was a girl in my freshman class who was 15 yrs old (she had been homeschooled). Because she was so young, she couldn't participate in some of the activities that we participated in (and I'm NOT talking about drinking!!), because the events were only open to people age 18 and over. That left her very depressed and lonely, because few people wanted to be friends with someone so young. After graduation, it was very very difficult for her to find a job because so few employers wanted to deal with a teenager (she graduated at age 18), even though she had a degree. During college, she never really fit in, because her contemporaries were still in high school (when she was graduating from college, some of her peers were just graduating HS), and her fellow college students were all so much older than she was and were interested in other social outlets than she was. She was just "there" and was sometimes used by other students. People who knew how smart she was promised her friendship if she did homework for them, and when the work was done, they never followed through on their promises of friendship. While many of her so-called "friends" in college were preparing for serious life-long romantic relationships, she was just beginning to develop an interest in dating. Not many people wanted to hear about her experiences in scouts, or drama club, or how she had a crush on someone--everyone was past that part of their lives. She told me on several occasions that she wished she would have just gone to private school, taken college level courses for credit, and graduated with people her age. She was too young for sororities, too young for some parties, etc...so her college experience was less than it couls have been. 
My point with all of this just shows that while your child may be extremely academically advanced, there is still a world outside of academics that comes with school. Sure, they may score higher on standardized tests, but that means nothing if they don't enjoy their own intelligence. When I tested as having a high IQ score, my parents put me in a "Saturday Scholars Program" for people my age, which allowed me to get the intellectual input I needed, and still graduate with my peers. So no matter how you school your children--homeschool, public school, or private school, don't forget to consider what comes later in life. Scores on tests are NOT everything. Let your kids be kids while they can because they can't get those years back. While they're just hanging with their friends, they are learning. Not all education comes out of a dusty textbook.