I'm really torn on this. While I do understand why Cruise Lines are doing this (having witnessed how many people don't show up on the last night) I too like to have control. In the past Carnaival suggested $3.50 per day for the waiter and $2.00 per day for the busboy and $3.50 per day for the cabin stewart. Now with prepaid tipping, they charge $5.50 per day which includes the Head Waiter, and two table waiters, $3.50 for the cabin stewart and .75 cents for the Lido staff. The last cruise we sailed on we hardly saw the Head Waiter until the last night! The $5.50 we would pay to the Waiter and Busboy is now split between three people! I don't like that.
I've heard that Carnival will leave vouchers in your room the last night to give to the dining staff (that's fine), but I still think I will have the tipping removed and tip accordingly. I still think the waiter and bus boy deserve more than the Head Waiter. On the other hand, if its a hassel (with line ups etc) reversing the charge, I hope I can still give additional tips, in cash, to the appropriate staff member.