Absolutely - pitch a fit. Do you have documentation of the lowest available coach fare at the time of booking (e.g., a screen cap of the same itinerary at about the same time you booked your first class ticket)? If so, send it to AA and request a refund of the difference.
http://www.aa.com/i18n/customerServi...ge.jsp#Refunds

If that doesn't work, file a complaint with the DOT Aviation Consumer Protection Division (http://www.dot.gov/airconsumer). You can also try a chargeback with your credit card, but if the charge was on a bill dated more than 60 days ago you may not have any luck.

You can try an ombudsman service in the media, I forget the name of the guy who is known for this.

If all else fails, you can go the small claims route.

Good luck - AA's downgrade "compensation" from these tickets is highly offensive, particularly since there is no indication during the booking process on AA.com that these are not first class fares (if it looks like a duck...).
This whole racket really needs to be shut down.

One word of warning - AA will probably claim the downgrade was voluntary - they likely offered you coach on the next available flight, or first class on a later one, and you chose coach. I guess the question is whether they told you what the refund would be at the time you made that decision. That said, I don't think it should matter, though some will disagree.