As I said earlier, widgets are supposed to be so easy to use that you don't need to learn anything. They are not for complex tasks - either they just sit there, or they have the one button that says "DO STUFF", or something along those lines. Interface consistency is important in a big and complex program, but nowhere near as important in a program that lets you change the song in iTunes.

Furthermore, remember that widgets are just HTML and Javascript, not Cocoa or Carbon programs. Not conforming to the usual Aqua look makes things much easier for developers.