Part of the reason was that it's easier to return to main page if you are using a subpage. Secondly, I absolutely hated how many redlinks the hardwired Gallery link in the infoboxes created. If there is a need for a gallery, add it to the main page first, and if it gets to big, someone will come around and create a subpage.
In addition, I want to note I am hoping to achieve a larger site overhaul. It's a bit of a work in progress.
> Users could make their own galleries first and implement their own images. Now they cant make it or even enter their own gallery.
and the interface would redirect you to creating a new page. Either that or using the Special:CreatePage and enter "Patty/Gallery" as the name. It's the same process as creating pages for anything else.