It seems a lot more expensive to you because you're not only upgrading resorts, you're also upgrading your dining plan. Plus, in the last 24 hours, the moderates are apparently filling up on the FD offers, and their prices have jumped quite a bit. Also, I imagine that most that experienced only a marginal increase had upgraded their QS dining plan to the standard dining plan.
Here's my real example. 2 adults and one child, but the child is 10, so in Disney terms....3 adults. 6 nights, 6 days in the parks. We originally booked at POP, and we upgraded to the regular dining plan from the QS plan. Total of that stay was $2376. When standard rooms opened up at CBR, we upgraded to that deal and our total cost went to $2491...or a $114 increase. We've since moved to CSR for the same deal.
Upgrading from the QS dining plan to the standard dining plan added something like $340 to the original reservation at POP.