Brajesh,

Cover image would work as the Edit Gallery allows you to edit or delete the current cover image, so changing it to a featured image would probably cause me all kinds of PHP headaches.

I want to be able to add the cover image, or the first image to the gallery, through the gallery creation form.

This would be similar to adding a featured image when you create a new post. My thinking on galleries having actual featured images is that when you delete the cover image, it removes it from the gallery too, which can be a bit confusing for the end user. By using a featured image, deleting it wouldn’t effect any of the images in the gallery.

Again though, this is a rather small thing that’s generally easy enough to deal with so actually converting cover image to featured image isn’t necessary, just the ability to upload a cover image during gallery creation.

Thank you,
Becky