Do you mean it's not their intent to create class separation or that it is not the result?
I think their intent is to make money where they see the opportunity to do so. I don't think class separation is in play here at all. It can certainly be the result without it being an explicit goal of the offering. Yes, your point about that the price reflects the demand for the service is correct. Enough people are willing and able to pay for a reserved seat instead of standing for the show that the $60 price tag is not "too much" in the sense that they are using price to allocate a scarce resource. (In fact, I'd like to run some price-tinkering experiments and see if they couldn't sell it out at $100 a seat, given how few seats there are compared to the number of people trying to watch the show.) But, as with first-class airfares, I suspect that the average household income of the people sitting in the reserved area is higher than that of those standing below. So the effect of a family needing to spend hundreds of dollars to utilize Fantasmic seating is that richer families are more likely to use it, thus separating themselves.
If one were only able to view Fantasmic by paying for seating, I would agree with you; however, anyone with time, planning, or luck can get a great view for "free".
Does that mean a family of modest means might not save up for a long time to have a "first-class" trip and splurge on extras like this? Of course they might do so. And a well-off family might have people who balk at having to pay on top of the general admission or feel that $60 for a 20-minute show is not how they care to spend their money. But the point about the average incomes of the two types of Fantasmic viewers stands.
It is a matter of priority. My priority is visiting Disneyland; some families' priority is McDonald's. So they buy their kids a $5 Happy Meal once a week, and I use that same money to buy my kids Annual Passes. It is true that Disneyland attracts more advantaged families, but I feel that is in part to the misconception that it is incredibly expensive. I'm honestly not sure whether Fantasmic dessert buyers are more well off than the average Disney attendee, or whether they are average DL visitors who are aware of the availability of this experience [I was not until reading about it here] and opt to add it to their vacation budget.
Sorry, I had to interject as so many people seem so strangely offended and miffed about the mere suggestion that Fantasmic dessert viewers are richer. You don't have to have "I'd like to avoid the hoi polloi" as a goal to still have it be a result of choosing to pay the extra money for those dessert seatings.
AJ