[Tokumonkey]

I can't get a 7 out of Drive even when I squint, and for Ghost to fit that "pattern," it would've had to be something visible in the Ore Damashii design.

Here's my very weak hypothesis: someone in the design team initially intended to include it in Wizard's design/concept, but it was dropped specifically because either (1) putting five of those chunky costume rings on the suit looked terrible, or (2) there'd been an initial fifth base form (flame, water, land, hurricane) that never made it past the design phase. Perhaps someone in the design process said, "Yeah, that was fun, but what the heck are we going to do when we get to seven or nine? Let's not do this just for the sake of doing it."

I wouldn't necessarily find that more likely than that it had been a coincidence to begin with.