The hands-off launch is used because the steam catapults produce peak accelerations high enough to cause a temporary loss of pilot consciousness. The new EM catapult systems may reduce the peak launch accelerations experienced by carrier pilots so it is less of a problem.
Drivers of NHRA Top Fuel dragsters and Funny Cars experience higher peak acceleration rates at launch than carrier pilots. Occasionally up to 8g's at launch, during a run lasting less than 4 seconds at top speeds over 300mph. The drivers wear neck braces and mouth guards to keep from damaging their teeth or biting their tongues.