I guess it could simply be a matter of numbers.
For guys seeking women on those dating sites - maybe you have to send 100 emails to 100 different girls (and maybe make them all individual - you never know which ones of those girls are friends especially if they live in the same area), before you get one reply. So if you send one email, you can't be disappointed if you luck out. I don't know what the actual number is for dating sites, but it's probably written up somewhere.
I apply the same system to job hunting. If I put my hand up for 10 jobs, I might expect one or two interviews. It depends on what job market you're in. Eg LA acting industry - I think it might be much higher like 1000 tries before you get one good response.
The other thing you can do, that might help get some response from the girls, is change your profile a little bit each week. The best advice I ever saw, ie it got the most interesting ad to me, was one that said write a little bit (no not everything, just highlights) about what you did the previous weekend. Then you get something that tells everyone a little bit about yourself and whats important to you.
For example
Last week I saw Pirates of the Carribean 2 with some friends I still have from uni (20 years ago). Johnny Depp looks like he was having so much fun. I thought it was a little long but I could see why they included the mill wheel fight, though it added nothing to the story. The special effects were spectacular, and gooey. I also went house hunting. Saw various houses including a couple of money pits (cf movie "the money pit") but none that gave me a warm homey feeling when I walked in and looked around.
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Something like that sure beats "I like going to dinner and the movies and long walks on the beach". I like stuff like hiking and long bike rides too but I hardly ever do that kind of thing so if someone hooks up expecting this is how I spend my weekends, they are going to be horribly disappointed. But mostly writing the basic same old same old - doesn't help you stand out from the crowd. And on these sites - the men need to make themselves stand out any way they can.
I'm full of helpful advice here, but I have never put an ad up myself on one of those sites. I'd rather meet new people by getting out and doing things I enjoy.