Something I have been thinking about a lot lately too. Now, I am NOT a designer and I am the first to admit it (I call myself a cover-tyer, like a cover-band covers "real bands" because they appreciate the original so much and they usually can't write their own music, I cover "real tyers" because I appreciate the real tyers out there and I can't design my own flies to save my life) but I think what has happened is that tyers have found a super solid way to produce a certain movement with doing different things on the Front hook while sticking to a pretty basic rear hook. The front hook is really the hook that will ultimately decide the action of the fly. If it is weighted with dumbell eyes you will get a jigging hook, if you don't weight the front hook you will get a swimming or darting fly, then there are happy-mediums between both with deer hair heads, wool heads, etc.
The Double Deceiver is probably one of the bigger strays away from the normal marabou, schlappen, estaz, and rubber rear hooked fly. BUT it has a very specific movement and way to fish it compared to a lot of these flies. But there are other articulated flies that change it up a bit, the Articulated Double Bunny, Conrad Sculpin, Meal Ticket, Ice Pick, and a few others are pretty different.