Ok, so being a panel away from being a Phantom originally bothered me too, but then I decided in my head canon that the Striker design helped inspire the design of the Tie Phantom. Cool right? Right? Anyone?
Well, it works for me.
I guess that means that the Interceptor was developed out of the Striker and the TIE Advanced combined.
I just hope, with a grim expression, that they have a justification for why the heck these lil' dudes aren't in the original movies. "Atmospheric only" would be fine. I guess we'll see.