I'm fine with an 8-character limit with purchasable extra slots, however, $15 a slot is awfully high. Further, the game is limiting its income by limiting the purchasable slots to 4. Neverwinter has something like an upper limit of 24 character slots, allowing alto-holics the option of purchasing slots well beyond the starting 8.
Why limit income by limiting slots to 12? With the expansion coming out, imagine those who are at their limit being able to buy more slots to make the new class. The 12-limit needs to go. More purchasable slots = more money.