What is the consequence of using lag bolts without pilot holes?
Pilot holes are done for two reasons. One is to help prevent the stud from splitting and the second is to make the lag bolt or screw easier to install. The ease of installation is important because the head of a lag bolt can shear off when excessive torque is applied.
As long as your lag bolts are firmly holding the TV in place with no wobble in the mounting bracket you should be fine.