The sign, as in a recent photo from Dave, completely changes the image. I think in this case it transforms it from a formal exercise, albeit quite an attractive and appealing one, into something that's a step up from that. It anchors the image in reality, reminding us that this isn't just a graphical slice of beauty and form, it's a real thing, just as the sign in Dave's photo anchored the image in time.
Taking it out certainly makes this a different image, and if you like that one more, I'm not going to argue with it. Both the image here and the hypothetical signless one are fine work.