There was a posting made by someone who spent over $240.00 already in extra cartel coins. That alone, is equal to 16 new paid subs. I personally did not spend anywhere near that amount however, I did purchase some more coins for a bit of a gamble and fun on some bags. Between my paid subscription and my extra coins, I provided BW with about 3 accounts for the month. 2 of which would be considered new.
Just a couple examples here. But indeed, this is working just as they had planned. They are making money now hand over fist. I personally hope they continue to make money so the enjoyment this game brings to some continues.
No one, has said for anyone to purchase just cartel packs or underworld ones. There are other things you can purchase that do not include the gamble.
I like the Cartel Market a whole lot; I spent 1200 of my 1800 free coins on unlocking the twi'lek and zabrak racial unlocks and the rest of it on gambling boxes. It was actually quite fruitful!
I don't have a problem with the gambling stuff just because it's totally optional. You can choose to buy it or you can choose to know what you're getting - it's your money and your decision.