So it looks like this:

Crab drive keeps the omni-directional part, but doesn't change the orientation of the robot.

Swerve drive has omni-directional motion, as well as the ability to change the orientation of the robot.

Well, in all of my years in FRC (Almost 2!!! ), I've never seen a match where robots didn't need to change their orientation, so therefore, why would one use a Crab drive if it can't change robot orientation?

Are there any advantages/disadvantages to the loss of the ability to change orientation?