My suggestion is basically same as Srishti's with a few keyboard modifiers to help you:
- Shift eyedropper click on color you wish to pick up from placed image. Your fill
- In swatches palette click 4th icon on bottom to create new swatch
- Click gradient swatch centered under the fill and stroke in tools, or use > shortcut
- Select a gradient swatch in the gradient window
- Option click a swatch in swatches to fill the gradient swatch
- Draw a vector shape and that will be filled with the new swatch
You can contact the programmers by using this link
Illustrator Feature Requests: Top (1616 ideas) – Adobe Illustrator Feedback
My suggestion is to first search to see if you suggestion already exists, and vote on that one. Your chances of this getting updated are better if the vote count is higher rather than creating a new one and splitting the vote. much like in politics.