This thread bears the evidence of the impatient and non-empathetic society we live in. It doesn't seem like it was the kids fault they were "already running 15 minutes late."
How are the parents or the child infringing on your rights? were does it say on your ticket or anywere else that you have the "right" to quiet time anyway? If you want totall quiet and serenity, I would argue that riding on a jet aircraft is not the place for you anyway.
The reason they were kicked off was that the child wasn't in the seat with the seat belt fastened. Now we've all seen people on cell phones, kids with gameboys and even other adults being unruly and delaying the flight for one reason or another.
Give the parents a break. If they would have spanked the kid, someone would have them kicked off and arrested anyway for child abuse.