The Quick and Casual vouchers are actually a bit cheaper than the AK Meal Deal...they are only $11.25. We prefer the Meal Deal, however, because they provide a bit more flexibility. For example, if we use the Q&C voucher at Flame Tree BBQ (our favorite at AK) we will get a meal, a drink and a dessert. The Meal deal provides the meal and drink but then a choice of ice cream or popcorn later in the day, along with a bottled water or soda. Since we don't care for the desserts at Flame Tree we go with the Meal Deal, get the ice cream later and save our vouchers for another park/resort.
As for whether the deal is still available, the menu signs at each restaurant now specifically mention the meal deal so I would guess it is permanent.