I completely agree, SB cards need to go now that the majority of low level bots are gone.
A reasonable compromise could be:
unlockable from the start by burning 1x CP plus 1 Voucher per card to incentivize combining cards
burn value after unlock = 1x CP.
I'd like to repeat that now that most bots are gone oversupply shouldn't be an issue therefore SB cards have no reason to exist the way they are now.