I guess before the internet, your first question to a guy was "How old are you?" If you had an interest in dating him, why ask his age, then age must be your only/major criteria? If I find I connect with someone, I am not interested in how old they are providing they are adult, I am more interested in knowing about them as a person, and I don't believe I am the only person who thinks this way.

How the site is set up has nothing to do with the question of should giving your age be compulsory. I understand that this enables members to filter their search, but there are filters for other parameters as well, such as height, weight, ethnicity, etc, and these characteristics are not compulsory to register. The fact that some members choose to search within specific age range should not mean all members must provide their age. I only search for members with photos, but not all members have to upload a photo, it is a matter of choice. There is no choice on whether or not to provide your age in order to register as a member.