Is there such a thing as...

[Another Dave]

Is there such a thing as an uncorrected converter lens?

I just tested a WC-E24 wide angle converter lens on my Coolpix 800, and was disappointed at the contrast loss and lack of sharpness. I know that there are tradeoffs that have to be taken in using a converter, and wonder if I could get better results if the lens didn't try to do so many things, such as correcting for geometry and for color.

Could a simpler wide angle converter be made, that has a known aberration profile, that could be corrected AFTER the photo is taken, say in Photoshop?

Wouldn't this allow for better quality overall?