It's not that you are with a couple of hot women, though that certainly would help your image. My two women friends were just average looking. The key is that a woman can approach another woman in a club in a completely non-threatening way, create a little social circle, and then include you in it. She can then pepper the conversation with all sorts of things designed to make you look good.
It's just a way of overcoming the barriers women would normally throw up if a guy approached her directly. It works. I picked up chicks in U this way a few times. I didn't plan to have "wing girls", it just happened I had female friends, and I'd go out with them, and sometimes they'd help me out a bit
Personally I have never scored with a woman that I just walked up to and met cold. I just don't have the skills to start up a conversation out of thin air, I come across as nervous, the woman gets defensive. But, I'm pretty good with meeting people in more ordinary social situations, and the wing girls thing creates those situations.
Interestingly, I think the OPPOSITE is true for women. Having a guy around can be a big negative on her chances of scoring in a club, unless the guy she wants is a really competitive/aggressive type of guy. Other guys will notice the guy hanging around, assume it's a bf, and tread carefully to avoid a confrontation. For a woman, it's probably better to have wing girls too, and anyway, guys are usually looking to pick up.
All that said... I am not sure I would pay for this service... if I was going to clubs a lot, I would still have a bunch of "club friends", and I'd probably just try and get some women club friends to do this for me as a favour. It's pretty sad if you have to hire women to be your friends...