An example of why this would be a good idea is wedding photography. This makes for an ideal way of archiving many images or sharing a collection of images within one file. You can have pages and pages of images within one PDF. There are exceptions to this - with TIFFs being a notable example - but most image formats do not allow you to have pages of images within one file. Most image formats allow for the saving of one image. Why should you convert an image to a PDF?
While PDFs can also include images, they are primarily used to distribute or archive documents. However, PDFs are more about text-based information. PDF files are similar to images in that they are static representations of visual information. This allows for the digital archiving, sharing, or distribution of that visual information. There are many different image formats out there, but they all have one thing in common: they preserve visual information in a digital form.
