Not surprising -- it seemed like a marginal route. In the brief time it lasted, it was a great "emergency option" for redeeming standard award tickets. I never had to use it, but I noticed it was the easiest AA EZE route to get tickets on.
Oh, well. Many long haul routes are getting cancelled these days due to the crazy fuel prices. US cancelled their new PHL-Beijing flight before it launched because the annual fuel bill was going to be $90 million. So you can get a sense as to how much dinero we're talking about.
I suspect all non-MIA US routes to EZE are vulnerable if oil doesn't start to pull back.
http://biz.yahoo.com/prnews/080527/latu524.html?.v=10