As a photographer myself I am very unhappy to find that this is happening because metadata is very important for EVERYONE that handles images.
Here are a few reasons why:
Copyright and other rights associated with the image
Contact information of copyright holders and licensors
Artworks, buildings and people portrayed in the image
Search terms (keywords)
Technical details of the photography
Rights restrictions for use of the image
Rights granted under a licence to use
I had the same issue, which is totally unacceptable, so I did a bit of research. The good news is there is a way to preserve the essential metadata... I hope to post more in the future but for now here is what I found thanks to my photographer colleague at http://www.photometadata.org
Here's how to fix it: http://www.tuchesaufntish.com/2011/05/27/preserving-metadata-in-images-uploaded-to-wordpress-sites/
You may have noticed the bad colours on thumbs and poor saturation of your images on WP... I think you will find IM as described a huge improvement.