My earlier reply to this was a joke, of course. Kinda surprised I got a thumbs down on it.
The guys expect to see pictures of the ladies, so they can find someone that is appealing to them. Makes perfect sense. It also helps guys know what to expect when they meet a lady, and if photo doesn't match the lady, it sends up red-flags.
So, there is the question about a guy sending a photo, if requested. A guy doesn't have to, and as has already been mentioned, refusing to send one can result in a lady refusing to see the guy. That's fair. But, guys have to worry about being exposed, and who's hands the photos will land in. Also reasonable.
If a guy's photo is already out there in the ether, there may be a way to just send a link to it, if the link was to a site that wasn't identifiable. Maybe a free Dropbox account tied to the guys user name here, and the dropbox containing just a photo? Clunky, yes, but it might work.
Just thinking out loud.