1. They couldn't get the other planned subjects to sign permission/contracts etc (doesn't seem likely as most of the top players of the day appear in OPC, V252, V357, and V129 so that couldn't have been to difficult or expensive).
2. They skip numbered as a tease to get kids to keep buying packs looking for the missing numbers. Sounds cynical but remember some of the SPs from sets from the 20s meant to make it difficult to redeem the cards for prizes.