I can see where you're coming from. Currently skill refunding is really the only gold-sink of the game, and people get around that by respeccing. Also, in the early game when you'll be wanting to test out skills, they're probably the most expensive to refund, as refund price scales with level, but you level up too quickly for cash drops to scale up with it. I'm not sure that a mindwipe potion would be the best way around that though. Probably different cash-scaling might be a better solution.
I've talked about name changes, sex changes and spray tans in another thread, so I'm also with you there. However in potion form it seems a little weird to me. Seen as we already have a character which the player can talk to to change haircut or colours of clothes, it would make more sense to expand upon that in my head.