I can see both sides of this for the sake of manufacturers, if there is to be a default it should be either Both boxes ticked or both boxes Unticked, so we have Show Other/Unkown and Blank Panels.
There is honestly more interesting stuff in having Show Other/Unkown Ticked than the Blank Panels.
Enjoy your spare HP, don't rush to fill every last space, this is not like filling sticker books. Resist the urge to 'complete' your rack, its never complete so just relax.