It appears Sun tried to add all possible features without concern for performance or system requirements. Swing's behavior on a 32MB 200MHz Windows 95 system is too slow and sometimes painfully slow. Sun has stopped development of Swing for Java 1.1.x, so there is no more opportunity for bug fixes or further development without switching to Java 1.2, which is much slower. Although you probably won't ever need to, the behaviour and appearance of Swing widgets is not changeable without agreeing to the Sun Community Source license. We have not seen AWT source code.
Small components are useful for making property list dialogs.
There seem to be several toolkits which extend AWT, but few alternatives to the basic components. SAWT - now officially discontinued in favor of the GNU classpath project. Says to use Swing instead. RemoteAWT - at IBM alphaworks. But not implemented as AWT replacement.