Personally, I think it's a terrible idea, and o_e_l_e_o pretty much nails it on the head on why.
I think
Photo Seeds has a fundamental flaw:
Odds are much higher that someone will remember a photo or a number of photos, and the order of those photos before they remember 12 random words.
If you've ever played the memory game (kids are much better at it than adults), you'll know you can barely remember a few pictures. And every new picture you see makes it more confusing.
While I do agree with the majority here, photo seeds or generating a seed via photos isn't a good idea mainly due to the metadata issues brought up, I've always thought that pictures are easier to remember than words. In fact, a common memorisation technique "loci" is basically assigning whatever you want to remember in a particular order, and basically imagining images in your mind.
For example, a logical one is a house, which is located on 12 seed lane (imagine a street sign), then you memorise the rooms, so first you go to the front door (word number 1), and you picture a massive red door, then you enter, and go through door number two, which upon entering you picture a donkey playing drums (second word "drums"). So on, and so forth. Point being, images are much easier to remember than some random word.