I don’t feel pressured to share photos – in fact, I think it’s the absolute bare minimum (along with a filled out profile) that should be expected of me if I expect to have a conversation and eventually meet someone.
I’m not personally concerned about my safety or privacy (scammers, phishers, and blackmailers can be a problem in online dating, but can be spotted a mile away), and I’d much rather a potential match be able to decide if she’s interested before a conversation starts.