I would home-school if:
a) I had a child
b) my town population was greater than 10,000
There could be other factors, of course. The population is key to me. I just love small towns, I guess.
Think of this then: In a small community, your say has ALOT more clout than in say... Fulton County (Atlanta)
Public School may be best for you, and worth fighting for, but that's because you are on equal footing with anybody else.
In big towns, your voice is easily lost.
So this would argue that one should homeschool when the public school is at odds with you (and likely would remain so) And let them go to public school when you have a better say in things.