Can I ask.. why on earth are so many people here being so judgmental about what is, essentially, a personal choice?
I have a number of GOOD friends with whom I sometimes have benefits. And I can tell you, there is most certainly an emotional connection. There is not a committed, structural relationship, but how the heck does that mean I cannot have love for more than one person? For these people in my life, the friendship and love come first.. the sex second. I generally don't have casual sex, and its a bit odd that someone would call FWB, universally, casual sex. It could be, if someone was doing it in that way I suppose.. but the term FWB has the 'F' first, and so it means you need to have an emotional connection BEFORE you have sex.
The OP, back in 2012, said they thought FWB was emotionally immature. I strongly disagree. In fact, there is a great deal of anthropological evidence that this is how most of us functioned before agriculture came along. Plus, there is a flourishing Poly/Open community out there, and I can tell you, there are a significant number of aspies in it.
Also, I suspect it depends pon where you are. Here in the SF Bay, there is a large Open/Poly community doing very nicely.