This new image resizing behaviour is strange for me, too. I want to see picture (and I want other users to see my picture) as it was uploaded. I do not want to see damaged, shrinked picture with poor quality. I know, there is possibility to see it as it was uploaded, but try to do it for 20 pictures in one log. You will click your mouse button to death and waste lots of time. This is not good design at all.
If you want to have this fancy image resizing (after clicking on pic link in listing/gallery) to "unify" displaying of all pics, please consider to add user setting (simple check box "I want to see always original pictures"), which will disable it and display always original pictures.
Please, do not damage user creativity and will to share their pics with your "website design".
Thank you.