While your point is valid, I'm left wondering if too much openness becomes a problem. When I was single, I made an OkCupid profile and decided to, for better or worse, be as open and honest as possible (a principle I adhere to in meat space as well). I had over 1200 questions (this is a lot) answered and never tried to make myself seem like something I wasn't.

I figured I was doing everything right, and I was optimistic (a good handful of my friends had great success on OkC), but I barely got any dates, and the ones that I did ended up being duds. I did this for maybe 8 months.

Contrast that to the couple of months I signed up for a paid match.com account (pro tip: paying for a service and looking for someone else who has paid for a service shows a mutual seriousness about the service; OkC's barrier to entry is practically zero so many people don't end up taking it seriously) and here I am with a going-on-three-years-now happy relationship. Match barely has any information to fill out and it makes me wonder if that ends up being a more successful model, as it pushes much of the "screening" process to meat space, where it's a lot easier to discern people's idiosyncrasies.

Of course, being open once you're offline is absolutely key. I'm just not sure how well it works for the first online impression.

Edit: I don't mean to attribute my relationship success to my choice of service, that was pure luck. I just wanted to point out that it'd be interesting to see more data about openness' influence on dating site success rates.