To expand upon a well-known saying:

"Never attribute to malice or specific intention that which can otherwise be attributed to incompetence and/or indifference."

It took me a while to understand, but Sharklets on AA mean that in business/first you will have lay flat seats instead of a recliner. I agree that there is a beter way to show this on the booking page. This type of aircraft is also shown as A321T, where t = transcontinental (I think). And you will see this back in the price, as these flights are typically much more expensive.