ActionScript 3.0 :: Loading Bitmaps Into BitmapData?

I want to load .jpg images into flash and store them as BitmapData objects. I've coded the loading of images many many times but I've never tried to store them as BitmapData, I just usually add the Loader to the display list and manipulate the image through its loader.

I feel like this is a very poor approach and so I want to try just saving BitmapData, because on the Model side of things thats really all I need.

Now the only way I have found to extract BitmapData from a loaded JPEG is to load the JPEG and upon completion write:

myBitmapData = Bitmap(loader.content).bitmapData;

First, is there a way to extract the BitmapData without encumbering the code with the Bitmap class? In other words, is there a way to extract that information without involving the Bitmap class - BitmapData while useful for a Bitmap is not dependent on Bitmap so ideally I would never involve Bitmap here.

Also, why is this Bitmap type-casting so widely accepted? loader.content is a DisplayObject and therefore is not necessarily compatible with Bitmap. Further, for all Flash knows we just loaded an SWF and as far as I know you can't typecast that to a Bitmap.