why would you not get cards?
I almost always get cards. No card and big bets = quick call to surveillance. Cash back has probably acoounted for about 20% of my cumulative win at BJ. that is not counting comped rooms and meals. Without getting comped rooms and meals, most trips would be cost prohibitive. Once you get backed off on a card, if you come back giving no card you are at the same point.
I recently got a $1000 cash (chips) from a casino I was told no more BJ about a year ago. i went in got the chips, played them at craps table (a few hundred at a time), cashed out and left. Had I never given a card at this place, I probably would have been told no more BJ a lot sooner and probably missed out on about $5000-10,000 in cash/coupons + about 10 free nights and too many buffets.