I don't see the fascination either.
My facination with a QD VFG is this:
For CQB use I like the VFG.
For distance use I like to go with a naked bottom rail.
I just like the ability to change applications at the drop of a dime. It's really more practical than it seems.
I've tried to like the falcon QD grip many times (bought sold bought sold bought again and just threw it out), but there are those sharp edges on the underside of the mount / top of grip area that ruin it.
If it wasn't rubber coated, I'd just drmel the plastic/metal that was there and have a solid VFG. They are onto something though. adjustable mount tension, great compartment, great grip shape (minus the sharp edges!) good feel, etc.
I'm not so into VFG's preceisely cause I can't find the grip I would want. My perfect grip would be the SOG BMX grip with a larue QD mount built into the top (just added on would make the grip too long).
Or you know what would sell like there's no tomorrow - a slightly shorter grippod with a larue QD mount.
But back to my point, the falcon's are cheap enoguh to get and then try out, but be warned about the sharp edges.
ETA: the fascination with QD is why we like AR's in general - modularity. I can go from a QD Harris benchrest bipod, aimpoint 3x and tripower and VLTOR A1 clubfoot on a table, to standing up drills using a VLTOR carbine stock, just a tripower and (if I liked one enough!) QD forward grip in under thirty seconds. For me its about convenience at the range. But practically, I always thought a warfighter could increase the effectiveness of his rifle by carrying a QD VFG, QD bipod and QD 3x in his bag..... then his single carbine becomes two or even three if needed.