They've painted themselves in a corner. They can't drastically reduce the costs without pissing off the 4 people who bought them at an arm and a leg.
Sure they can. Early adapters pay more. I paid $50 for this game at retail. Now it's a free download. Even if I find one of those mystical retail boxes again, they only cost $10-15.
I also bought the DDE. It cost me $5. I don't remember what it cost originally, but it was more than $5.
I paid $10 for RotHC. That's free now.
Items get marked down in the CM all the time.
Adjustments happen. Things aren't set in stone once they are implemented. If this scheme proves unpopular, they will either stop doing it, or drop prices. If it has worked well for them, we will know, because they will offer the deal again later at the same price.