So my photo was chosen for featured image (for which I'm very grateful), however I noticed that it looks darker than I the image I provided, and as I suspected the colour profile has been removed from it. Is there any reason for this?
The color profile (and all exif data) is probably stripped out as part of the publish in order to conserve bandwidth. This is often done when you are dealing with an image that is going to be pushed out to every person who comes to a website, with 3000+ visits a day, even small differences in the file size can be significant.
As mattdm mentioned, the easy way to deal with this is to use srgb, since your browser will default to that anyway.