You can get a lot of the gold benefits just for having a AA co-branded credit card, like priority boarding and a free checked bag on domestic itineraries. Gold status will get you that free checked bag on international itineraries, and a shot at upgrades. Once you earn gold status you start getting 500 mile upgrade stickers -- four every 12,500 miles you fly. You can collect these like a squirrel collects acorns and use them at some point in the future if you have higher status. You also have a good chance of clearing upgrades if you chose to fly at unpopular times (for example, Christmas day).
Gold status also gets you free preferred seats, which your credit card won't get you. Within 24 hours of your flights, you can select a MCE seat (if there's one available) and get free booze too, a credit card won't get you this benefit.
If you value OneWorld Ruby status at all (I don't), you'd get that too with Gold status if you chose to fly another OW airline.
You could also consider becoming elite in another OW program, your benefits will be better once you hit OW Sapphire (free lounge access)