hahnmeister - you're absolutely right and I didn't even think of that at first. It would be impossible to remove the plate if it were one solid piece. This eliminates the need to make the bottom removable like we see on ATB, BK, etc.
BTW on the bubble plate they even routed out the top of one piece and bottom of the other along the center line allowing them to "seat" nicely and prevent a gap.
Here is a picture of the BOTTOM of the bubble plate after being removed:
