Unfortunately, thanks to the "archive" view (which is a fantastic way to view your images) simple sortation isn't the only problem with having the wrong datestamp.
I think ctime is a problematic way to approximate the date of a picture's creation, as ctime is an unreliable measure of a file's creation date. It's simply a system representation of the date that the inode for the file was created.
While some operating systems (MacOS X, for example) have a separate "date created" timestamp on files that is separate from the date the particular instance of the file was created, most Unixes have no equivalent. We can only tell the date of a distinct instance of a file on a given filesystem.
In MOST cases, mtime should match ctime in the case of an uploaded file (it was last modified and created when copied from the user's camera, and again, modified and uploaded at the same time). Unless the core file is updated on the server (an odd thing to do once it's already in a photo gallery), the mtime and ctime ought never to be out of sync.
So, from a functional perspective, mtime seems more useful because it can be reliably maintained through backup and restore processes and is also user-modifiable, so users can sort their photos as they wish. And in most cases, mtime and ctime would be in sync, anyhow, so from a general usability standpoint, the gallery would work as expected.
In my case, I had to recover my files from a backup, so each was created as a new inode (on a new filesystem, for that matter), with updated ctimes. The files themselves were last modified on upload date (the restore process correctly maintained all the file metadata it could).
Of course, if EXIF data is present, none of this is an issue. Many of my files lack this information because they went through batch changes from RAW to JPEG to simplify uploading, and the program I used didn't maintain that metadata. Now I know better.