Although I wouldn't do it, I really do not see this as being that crazy or out of line when considering some of the other expensive options at Disney World.
For example, people routinely spend $800-$1,000 a night for a room at the Polynesian. A family of 4 could stay at a moderate resort, eat a couple of CS meals, and attend the evening after hours event for the same price that another family of 4 spends just on their room. It's all a matter of what you prefer.
Another example, although I love eating fine food, I would much rather spend $150 for the extra evening hours (assuming they truly do offer drastically reduced crowds and walk-on at all the rides) than spend $250-$300 for one meal at Victoria & Alberts. Last I heard, V&A's was not exactly having to beg people to eat there. Again, it is just a matter of spending your money on what you prefer.