Many of the worm-drive circular saws have the blade to the left of the
motor.
Visibility to the line of cut is typically the reason. The saw is still
held in the right hand using the left hand on the knob.
Having both RH and LH saws means that the weight of the motor (and the
bulk of the shoe) can be oriented over the larger piece of lumber or
plywood. when cutting near an edge.
Safety glasses are even more important when the blade is closer to the
user's face than the saw motor. The body of the saw no longer blocks
the chips that fly out the side of the blade guard.