One thing to keep in mind is the type of riding that is being done. An IBR participant or even the guy on a long weekend trip is going to have different cooling needs than the commuter or the day tripper who doesn't go more than an hour at a time.
Holding in moisture and preventing air flow to my skin is something I actively avoid. I wear mesh in the summer and it gets well above 93 here in VA. Its also a very humid 93+. I want all the air flow I can get for my 37 mile commute. I want the take advantage of any evaporative cooling that can be had. I am never more than 60 minutes away from a big gulp of water and I stay well hydrated before my commute so dehydration just isn't a concern.
What is not possible is to soak my shirt, put ice on my neck or soaking my head. None of that gets me to my destination in a condition in which I can work.
I'm not riding to ride. I'm riding to make it to and from work in the most enjoyable way possible. Mesh makes a big difference for me. I understand the down side in longer distance riding but for me, its the best solution.