I realise Illustrator is a vector drawing program, but a lot of us use it to build dynamic user interfaces to output bitmap graphics. There are tools to export bitmap images (save for web and export as PNG) to this should also be optimised for it. One area that illustrator is really lacking in outputting good quality bitmap graphics is the lack of gradient dithering that can be found in photoshop.
Marc Edwards has a great writeup on this.
I'm sure it could be implemented as an Appearance Effect since dithering occurs at a pixel level.
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