Hot Damn! As an author, I know I got not one penny more after prices were jacked up by Jobs and company. The money went into the pockets of the greedy publishers. They can make tons of money off selling new books at $9.99 because they have no printing costs, paper costs, distribution costs, warehouse storage costs or transportation costs. eBooks are extremely profitable. This was nothing more than greed running rampant among the publishers.
You may want to check your contract. Most publishers pay royalties as a percentage of net. So, one of three things is happening: the net proceeds your publisher received have not actually changed under the new terms; they made an accounting error; you're wrong. I encourage you to check your contract and make sure you go over your royalty statements carefully. Then, please report back to us.
Of course, if your contract gives a set amount royalty per book, then of course it wouldn't change.
The idea that publishers make "tons of money" and that "eBooks are extremely profitable" is, at best, a stretch.