The main argument I hear against homeschooling is 'socialization'... Personally, I don't want my kids to be around kids (especially at young ages) who can't behave. It's not like homeschooled kids are stuck in the house all the time. We get out, we go to the grocery store, walks, park (ok..maybe not the park so much-but that's more because I avoid the cousins who live by the park), church. They have interaction with humans other than mom, dad and grandma.
I do believe that homeschooling is just not for some kids or parents. Some people can simply not do it while others flourish in it.
As far as the academics and not being able to teach simply because you don't have a degree... Sometimes I wonder if public school teachers have a degree.. There are charter schools, programs to get into so you get all the curriculum and it's basically you helping your kid with homework-but for 4-5 hours a day instead of an hour at night. Or there's more hands-on approach where you get do all the planning and organizing and actual teaching.
One major benefit of homeschooling for me is that we can take vacations whenever we want. Pick up the books and take them with you, or plan special lesson plans around where you are headed.
You teach your kids every day. Why not do all the teaching?