Depends on the type of accident you are speaking of.
The FAA has determinded that children are safer in a car seat during a flight, take off and landing. Airplanes experience turbulance, little people are not adequately protected in an adult seat belt. Airplanes sometimes bounce during landing, again the same theory applies to the seat belts.
Also, children are, hopefully, used to a car seat and will tend to remain seated during the flight, thereby giving the parents and other passengers a peaceful flight. There is nothing more annoying than having a child screaming during a flight because he is being restrained by a parent not a car seat. Or, one that needs to roam the aisles with mommy and daddy to meet the other people because he/she cannot remain seated. That is a big annoyance to many people. We don't want to meet your kids, we want a peaceful flight. (I am not addressing you in this semi rant, btw. )
Wrong, I don't think so, I think it is a matter of personal choice and desire to keep your child safe.