I think making photos optional is a good idea myself. I've never required a photo on any of the 8 ECs I've published. There have been hundreds of finds logged, and of those I've deleted maybe a dozen or so because of poor or non-existent answers. But I see no evidence at all that anyone is passing around the answers and armchair Earthcaching. The whole point of Earthcaching is to learn something, and when it comes to learning, one good question is worth a whole page of text. A photo teaches nothing.
I'll be glad to see the photo requirement eliminated when it comes to the ECs I find too. I do most of my caching by myself and trying to take a decent picture can be a real nuisance. My digital camera is fairly bulky and I don't always want to lug it around with me when I'm caching. My cell phone is much smaller, but it's almost impossible to frame myself in the picture with the appropriate background. There have been some Earthcaches where I've spent more time trying to get the stupid photo right than actually exploring and learning the geology. And if Earthcaches make up a high percentage of the caches you do, your gallery ends up with a bunch of pictures of your big head blocking out the background, usually with some kind of goofy expression on your face trying to snap the picture.
And as for the idea of the picture being comparable to signing a logbook, just how many COs go out there and read the logbooks and check them against the online logs???