Whether AA should now or should have ordered the 764 or 333 is not necessarily a question that needs to be answered here... but to argue that AA can't grow because it doesn't have long-range aircraft. When you also consider that AA is using 772ERs for 8-10 hr international flights, then yes, it does make sense to ask the question why AA doesn't have a 250-300 seat aircraft that is designed for short to medium int'l flights instead of the 777 which is best suited for 12 hr plus flights - and because of that the 772ER weighs 50K pounds more than the 333 when both can do the exact same missions on most of AA's 772 routes.
You know, I didn't start this thread hoping to initiate an airliners.net-style discussion of all the different airplanes that AA should have ordered over the years instead of the 777-200IGW and how the combined DL/NW hodgepodge of fleet types better positions DL for the future. Nevertheless, you apparently can't resist advancing that view wherever someone will respond, so here goes. According to Airbus and Boeing, the 772ER is only about 35,000 pounds heavier than the 333, not the 50k you allege:
http://www.boeing.com/commercial/airports/acaps/7772sec2.pdf
http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus_AC_A330_Jan11.pdf
I see from the DL treatise recently posted in the DL forum that you don't like posting links to any factual sources. Perhaps you have some source that demonstrates that AA's 772s are heavier than Boeing indicates or that DL's 333s are lighter than Airbus indicates. Elsewhere, you recently posted that DL has a 15% CASM advantage to AA. You didn't indicate the timeframe for that assertion, but for full-year 2010, DL had a mainline CASM advantage to AA of just 10%. Are you playing fast and loose with the numbers? If you have the winning argument, there's no need to exaggerate the facts.
So in your learned opinion, the 772 is best suited to flights greater than 12 hours and suboptimal for flights of 8-10 hours. How many of those (12+ hour flights) did AA fly in 1996 when it decided to replace its DC-10s and MD-11s with the 772? I can think of two AA flights greater than 12 hours that AA flew at the time: DFW-NRT and ORD-NRT. Yet AA's management foolishly tied its future to the 772 and not to the A333 or the 764 (although AA did seriously consider the 764). Every other flight AA flew in 1996 was within the range of its 763ERs. Nevertheless, AA foolishly placed multiple orders for 772s that would eventually result in a fleet of 47 of them. All this despite the 772 being too heavy for all those 8-10 hour flights. While you might be correct, I'd bet that AA management took into account various factors besides the weight of the 772 in making its decision.
Of course, since 1996, AA has begun several additional 12+ hour flights, where the 772 is (in your opinion) a suitable airplane. Of course, no single airplane type can perform every mission in the most efficient manner. AA management has spent over a decade attempting to strike a balance between fleet simplicity and allocating the right airplane to each route. Perhaps that's been a management failure - if so, I think evidence of failure will require a lot more evidence than pointing out the weight of various airplanes that AA did not buy.
AA also has a long history of flying heavy, long-range airplanes on the transcons. I've flown on AA 707s, 747s, DC-10s, MD-11s, 763ERs and 762ERs between LAX and JFK. What will replace the 762ERs currently flown today? My guess would be more 763s as the 789s are delivered but it could be 757s. Perhaps even a 789 even though that's a large heavy airplane. DL currently flies at least one 77L on a domestic route to/from LAX, no? That doesn't sound efficient. But that plane's primary mission is the LAX-SYD flight and the LAX-domestic segment adds to network efficiency, right? For all we know, AA might decide the same thing once the 789s show up.